Method and system for changing electrode contact conditions - Patents.com

Abstract

To solve the problem of potentially making it difficult to rely solely on impedance measurements of a particular electrode in deciding whether the electrode is in contact with tissue.SOLUTION: A method of modifying a contact status of one or more electrodes in a plurality of electrodes located on a medical device includes measuring an electrical characteristic of each electrode in the plurality of electrodes located on the medical device, and determining a contact status of each electrode in the plurality of electrodes based on the measured electrical characteristic of the corresponding electrode, where the contact status is indicative of contact with adjacent tissue. The method further includes modifying the contact status of a first electrode in the plurality of electrodes based on the determined contact status of one or more other electrodes in the plurality of electrodes.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates generally to medical devices and systems and methods for detecting contact between electrodes in a medical device and adjacent tissue based on measured impedance. [Background technology]

[0002] Catheters are utilized in many procedures within the human body. In many of these applications, whether collecting data from surrounding tissue or administering therapy, it is important to determine the proximity of the catheter, particularly the electrodes collecting data or administering therapy, to adjacent tissue. Many methods are used to make this determination, including monitoring electrocardiogram signals (e.g., the voltage measured between the electrodes) and / or electrode impedance. For example, impedance is generally understood to increase in response to contact with tissue. However, many other factors can also result in impedance variations, including the location of the electrode within the body (i.e., different ventricles exposed to different amounts of blood flow may exhibit different impedance values) and movement of surrounding tissue, for example, as a result of the heart beating. Summary of the Invention [Problem to be solved by the invention]

[0003] These factors can make it difficult to rely solely on impedance measurements of a particular electrode to determine whether the electrode is in contact with tissue. Furthermore, such limited reliance ignores measurements and other relevant information from nearby electrodes. Therefore, it would be beneficial to develop a method for changing the status of a "no contact" electrode based on data collected from nearby electrodes. [Means for solving the problem]

[0004] According to one aspect, a method for altering a contact state of one or more electrodes in a plurality of electrodes disposed on a medical device includes measuring an electrical characteristic of each electrode in the plurality of electrodes disposed on the medical device, determining a contact state of each electrode in the plurality of electrodes based on the measured electrical characteristic of the corresponding electrode, the contact state being indicative of contact with adjacent tissue, and altering the contact state of a first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes.

[0005] According to another aspect, a method for altering a contact state of one or more electrodes in a plurality of electrodes disposed on a medical device includes measuring electrical characteristics of each electrode in the plurality of electrodes disposed on a medical device, determining a contact state of each electrode in the plurality of electrodes based on the measured electrical characteristics of the corresponding electrode, the contact state including "in contact," "intermittent contact," and "no contact," and altering the contact state of one or more electrodes in the plurality of electrodes based on one or more nearby electrodes having a contact state of "in contact."

[0006] According to another aspect, a system for use with a medical device having multiple electrodes and configured to be inserted into a patient includes a signal generator configured to apply multiple drive signals across different electrode pairs of the medical device; a measurement circuit configured to measure responses of the multiple electrodes to the drive signals and generate an impedance value for each of the multiple electrodes of the medical device; and a contact assessment module configured to determine, for each electrode, a contact status of each of the multiple electrodes based on the generated impedance value associated with each electrode, wherein the contact assessment module is further configured to alter the contact status of one or more of the multiple electrodes based at least in part on the contact status of one or more nearby electrodes. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a schematic diagram of a system including a medical device for insertion into a patient, the system being configured to utilize measured bipolar electrode complex impedance between electrodes to determine contact status of one or more electrodes located at a distal end of the medical device, according to some embodiments.

[0008] [Figure 2] 1 is a schematic diagram of a distal end of a medical device having multiple splines and multiple electrodes disposed on each spline, according to some embodiments.

[0009] [Figure 3] 1 is a schematic diagram of a distal end of a medical device having multiple splines, each spline containing multiple electrodes organized in a grid-like array, according to some embodiments.

[0010] [Figure 4] 1 is a schematic diagram of a distal end of a medical device having multiple splines, each spline containing multiple electrodes organized in a basket-like array, according to some embodiments.

[0011] [Figure 5] 1 is a schematic diagram of components utilized to measure impedance between two electrodes placed on a medical device, according to some embodiments.

[0012] [Figure 6] 1 is a flowchart illustrating steps utilized to determine the contact status of an electrode placed on a medical device using bipolar electrode complex impedance (BECI) measurements and the contact status of nearby electrodes, according to some embodiments.

[0013] [Figure 7] 7A and 7B are diagrams illustrating modification of electrode contact status for a clique based on the contact status of a 4x4 electrode grid with neighboring electrodes within the clique, according to some embodiments.

[0014] [Figure 8] 8A and 8B illustrate the modification of electrode contact status for another clique (single square) based on the contact status of neighboring electrodes within a 4x4 electrode grid in accordance with some embodiments.

[0015] [Figure 9] 9A and 9B illustrate the modification of electrode contact status for another clique (nearest neighbor) based on the contact status of neighboring electrodes in a clique with a 4x4 electrode grid, according to some embodiments.

[0016] [Figure 10] 10A and 10B illustrate modification of electrode contact status for another "nearest neighbor" clique based on the contact status of neighboring electrodes in the clique with a 4x4 electrode grid, according to some embodiments.

[0017] [Figure 11] 11A and 11B illustrate the modification of electrode contact status for another clique (four corners) based on the contact status of neighboring electrodes within a 4x4 electrode grid in accordance with some embodiments.

[0018] [Figure 12] 12A and 12B illustrate modification of electrode contact status for another "four corner" clique based on the contact status of neighboring electrodes in the clique with a 5x4 electrode grid, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0019] According to some embodiments, the claimed invention utilizes the contact status of neighboring electrodes to alter the contact status of one or more electrodes. The contact status or status of each electrode is determined by a measured electrical characteristic, such as a bipolar electrode complex impedance (BECI) measurement. For example, in the most basic example, an electrode's contact status is either "in contact" or "not in contact" with adjacent tissue. In some embodiments, an electrode assigned a contact status of "not in contact" or "no contact" is altered to indicate tissue contact based on a neighboring electrode being identified as "in contact" with the adjacent tissue.

[0020] As used herein, the term "adjacent" refers to multiple electrodes that do not have other electrodes between them. Adjacent electrodes may be located on the same spline as each other or on different splines, as long as there are no other electrodes located between them.

[0021] As used herein, the terms "neighbor," "neighbors," and "neighboring" refer to electrodes that are adjacent to each other and electrodes that are separated from each other by one or more other electrodes (non-adjacent). As used herein, the term "nearest neighbor" refers to electrodes that are directly adjacent to each other with no other electrodes between them.

[0022] As used herein, the term "clique" refers to a subset of two or more electrodes. An electrode may be associated with more than one clique. For example, a clique may include a group of three electrodes, and each electrode in a clique may be part of another clique.

[0023] 1 is a schematic diagram of a system 100 including a medical device 102 and a local system 103. In some embodiments, the local system includes a switch 108, a digital-to-analog (D to A) converter 110, a filter 112, an analog-to-digital (A to D) converter 114, a filter 116, a display 130, and an electronic control unit (ECU) 118. The electronic control unit 118 may include a signal source 120, a synchronization demodulation circuit 122, a contact assessment module 124, a memory 126, and a processor 128. In some embodiments, one or more surface patch electrodes 105 may be adhered to the patient's skin.

[0024] In some embodiments, the medical device 102 is an elongated medical device, such as a diagnostic and / or therapeutic catheter, introducer, sheath, or other similar type of device. The medical device 102 includes a distal end 104, a proximal end (not shown) including a handle that is manipulated by a technician, and an interface for interfacing the medical device 102 to a local system 103. The distal end 104 may include various sensors and / or components for locating / navigating the distal end 104 within a patient, mapping physiological parameters within the patient, and delivering therapy. In particular, the distal end 104 of the medical device includes multiple electrodes that may be utilized for one or more of these purposes.

[0025] In some embodiments, the contact status of one or more electrodes located at the distal end 104 of the medical device 102 is determined based on one or more electrical properties measured at the electrodes. For example, in some embodiments, the measured electrical property is bipolar electrode complex impedance (BECI) generated by driving an excitation signal between two electrodes forming a bipolar pair. The resulting voltage at each electrode is measured and utilized to derive a complex impedance signal. In some embodiments, the contact assessment module 124 utilizes the BECI measurements, alone or in combination with other measured electrical properties, to determine the contact status of each electrode. In some embodiments, the term "contact status" is a binary determination of whether an electrode is "in contact" or "not in contact" with tissue. In other embodiments, the term "contact status" may include additional contact statuses, such as "intermittent contact." In still other embodiments, the term "contact status" may refer to the proximity of an electrode to adjacent tissue.

[0026] In the embodiment shown in FIG. 1 , a signal source 120 is utilized to generate excitation signals. In some embodiments, the signal source 120 generates one or more excitation or drive signals, each with a unique frequency. More specifically, the signal source 120 may generate multiple excitation or drive signals with unique frequencies, in one embodiment, within a range of approximately 1 kHz to greater than 500 kHz, more typically within a range of approximately 2 kHz to 200 kHz, and even more typically within a range of approximately 10 kHz to approximately 20 kHz. Each drive signal may have a constant current, in one embodiment, typically within a range of 1-200 μA, more typically approximately 5 μA. The signal generator 120 may also generate signals involved in determining the position of electrodes within the patient's body, which may be utilized, for example, for mapping, navigation, and / or therapy delivery. The digital signals generated by the signal source 120 are converted to analog signals by a digital-to-analog converter 110 and supplied to selected bipolar electrodes via a filter 112 and a switch 108. In response to an analog signal applied across a selected bipolar electrode, the resulting voltage is measured at the electrode pair by switch 108, filter 116, ADC 114, and synchronous demodulation circuitry 122. In some embodiments, switch 108 selects the electrode to monitor in response to the applied excitation or drive signal. Filter 116 and ADC 114 convert the analog signal to a digital signal that can be manipulated by ECU 118. Synchronous demodulation circuitry 122 separates the signals from one another based on the frequency of the excitation or drive signals, allowing multiple bipolar electrode pairs to be analyzed substantially simultaneously based on the multiple excitation or drive signals applied to the electrode pairs.

[0027] In some embodiments, the memory 126 may be configured to store respective data for the medical device 102, the patient, and / or other data (e.g., calibration data). Such data may be known before a medical procedure (e.g., medical device-specific data, number of catheter electrodes, etc.) or may be determined and stored during the procedure. The memory 126 may also be configured to store instructions that, when executed by the processor 128 and / or the contact assessment module 124, cause the ECU 118 to perform one or more methods, steps, functions, or algorithms described herein. For example, without limitation, the memory 126 may include data and instructions for determining the contact status of one or more electrodes based on one or more measured electrical characteristics, and may utilize the contact status of one or more electrodes to alter the contact status of nearby electrodes. As discussed in more detail with respect to FIGS. 7A-12B , a determination that one or more electrodes are “in contact” with tissue may be utilized to alter the contact status of nearby electrodes. For example, in a simple case, a determination that a first and third electrode are “in contact” can be utilized to change the “no contact” status of a second electrode located between the first and third electrodes. In some embodiments, the contact assessment module 124 utilizes a processor, application specific integrated circuit (ASIC), or other type of processor that executes instructions stored in the memory 126. The ECU may be coupled to a display 130, which may display an output of the determined contact status of the sensed tissue (e.g., heart), medical device (not shown), and / or one or more electrodes of the medical device 102. Some embodiments may include displaying electrodes determined to be “in contact” based on sensed electrical characteristics and electrodes whose contact status has changed based on the contact status of one or more neighboring electrodes. In other embodiments, only the final contact status of the electrode is displayed, regardless of whether the contact status has been changed by the contact status of one or more neighboring electrodes. In other embodiments, the display of the contact status associated with each electrode is accompanied by a confidence level associated with the contact status.For example, an electrode that is determined to be "in contact" with tissue based on one or more measured electrical properties may have a higher confidence level associated with it than an electrode that is determined to be "in contact" based on the contact state of one or more nearby electrodes.

[0028] 2 is a schematic diagram of a distal end 104 of a medical device 102 having multiple splines positioned adjacent cardiac tissue and multiple electrodes 204a, 204b disposed on each spline, according to some embodiments. In some embodiments, the contact status of one or more electrodes 204a, 204b with adjacent tissue 206 is determined based on one or more measured electrical properties. For example, in some embodiments, bipolar electrode complex impedance (BECI) measurements are utilized to determine the contact status of each of the multiple electrodes. In the embodiment shown in FIG. 2, electrodes 204a and 204b form a bipolar electrode pair. The BECI measurements are generated by applying an excitation signal to electrodes 204a and 204b, resulting in a current flow between electrodes 204a and 204b, as indicated by dashed arrows 208a, 208b. At least a portion of the current 208a, 208b passes through the patient tissue 206 at the electrode-tissue interface, thereby affecting the inductive, capacitive, and resistive effects of the electrode response to the drive signal(s). That is, tissue contact affects the impedance measurements of the electrodes 204a, 204b. Generally, when the electrodes 204a, 204b are not in contact with the tissue 206, a circuit is formed within the patient's blood pool, and the BECI measurement is reduced. As shown in FIG. 2, when the circuit path includes the tissue 206, the BECI measurement increases, reflecting the higher impedance of the tissue 206, compared to measurements made within the blood pool. The BECI measurement is used to determine the tissue contact status of the electrodes. In some embodiments, the contact status may include a determination of "in contact" or "not in contact." In other embodiments, the contact status may include other contact conditions, such as intermittent contact or a range of contact conditions. In other embodiments, other measured electrical characteristics may be used, alone or in combination with the measured BECI values, to determine the contact status of each of the electrodes.

[0029] In other embodiments, the distal end 104 of the medical device 102 may incorporate a number of different shapes and / or designs. The embodiment shown in FIG. 2 includes a number of splines arranged in a basket shape, each spline including a number of electrodes. The embodiment shown in FIG. 4 similarly includes a number of splines, each including only a single electrode. In other embodiments, the distal end of the medical device 202 is a grid-like array of electrodes, as shown in more detail in FIG. 3. In other embodiments, the distal end of the medical device may be curved or looped with a number of electrodes spaced along the distal end. Similarly, a variety of different types, shapes, and sizes of electrodes may be utilized at the distal end of the medical device. For ease of explanation, altering the contact status based on the contact status of one or more neighboring electrodes will be described with respect to the grid-like array of electrodes shown in FIG. 3. However, it should be understood that altering the contact status of an electrode may be applied to any shape of electrode utilized to determine contact status within a medical environment.

[0030] 3 is a top view of a grid array catheter 300. In some embodiments, the grid array catheter 300 includes a shaft 302, shaft electrodes 304a and 304b, a proximal end 306, a plurality of splines 308a, 308b, 308c, and 308d, a distal end 310, and a plurality of spline electrodes 312. In some embodiments, electrical properties are measured at each of the plurality of electrodes and utilized to determine the contact status of the respective electrodes. For example, in some embodiments, bipolar electrode complex impedance (BECI) measurements may be performed between any pair of adjacent electrodes and utilized alone or in combination with other measured electrical properties to determine the electrode contact status.

[0031] 4 is an isometric view of a basket catheter 400. In some embodiments, the basket catheter 400 includes a shaft 402, a proximal end 404, a distal end 406, and a plurality of splines 410a-410f extending between the proximal end 404 and the distal end 406. Each of the plurality of splines 410a-410f includes a corresponding electrode 412a-412f. In some embodiments, an electrical characteristic is measured at each of the plurality of electrodes, including, for example, a BECI measurement, and is utilized alone or in combination with each other to determine the contact status of each electrode.

[0032] FIG. 5 is a circuit diagram illustrating circuit elements utilized to excite a bipolar pair of electrodes and measure the resulting complex impedance, according to some embodiments. Specifically, the circuit diagram includes a signal source 120 (shown in FIG. 1), one pair of electrodes 204a, 204b (shown in FIG. 2), first and second operational amplifiers 502a, 502b, and an ECU 118 (also shown in FIG. 1). In some embodiments, the signal source 120 generates an excitation signal that is supplied to the first and second electrodes 204a, 204b. The first operational amplifier 502a includes a first terminal (e.g., a positive terminal) connected to the first electrode 204a and a second terminal (e.g., a negative terminal) connected to the reference electrode 105 (e.g., a surface electrode). The output of the operational amplifier 502a reflects the voltage difference between the first electrode 204a and the reference electrode 105. The second operational amplifier 502b includes a first terminal (e.g., a positive terminal) connected to the second electrode 204b and a second terminal (e.g., a negative terminal) connected to the reference electrode 105 (e.g., a surface electrode). The output of the operational amplifier 502b reflects the difference in voltage between the second electrode 204b and the reference electrode 105. The outputs of the first operational amplifier 502a and the second operational amplifier 502b are provided to the ECU 118, which uses the respective measurements to determine a bipolar electrode complex impedance (BECI).

[0033] FIG. 6 is a flowchart 600 illustrating steps utilized to alter the contact status of one or more electrodes based on the contact status of one or more neighboring electrodes, according to some embodiments. In step 602, a medical device, such as device 102, can position its distal end within an internal cavity of a patient. The distal end can include multiple electrodes, as described above. As described above, various shapes may be utilized at the distal end of the medical device, including a basket-like shape, a grid-like array of electrodes, a curved spline, and the like. In step 604, after the distal end of the medical device is inserted into the patient, electrical characteristics associated with each electrode are measured. As described above, the electrical characteristics can include impedance measurements measured between one electrode or two electrodes. In some embodiments, bipolar electrode complex impedance (BECI) is measured between a pair of electrodes.

[0034] In step 606, the contact status of each electrode can be individually determined based on the measured electrical characteristics from step 604 for that particular electrode. In some embodiments, the contact status of each electrode is determined to be in contact or not in contact. In other embodiments, multiple contact states may be utilized rather than a binary determination. For example, in one embodiment, the contact states may be "no contact," "intermittent contact," and "in contact." In other embodiments, additional contact states may be utilized to convey various levels of contact between the electrode and adjacent tissue. In some embodiments, step 606 can be performed by an ECU that is part of the medical device's system.

[0035] In step 608, the contact status of an electrode is analyzed taking into account the contact status of nearby electrodes, and in some cases, the contact status of those nearby electrodes is utilized to modify the contact status of one or more electrodes. For ease of explanation, the contact status is described as being modified to indicate a higher contact status (e.g., from “no contact” to “contact” or from “intermittent contact” to “contact,” although the reverse may be possible in other embodiments). In step 608, only electrodes identified as other than “in contact” are analyzed to determine whether their contact status should be modified. That is, if an electrode is already determined to be “in contact” with tissue in step 606, no analysis is required in step 608 to determine whether the status of this electrode should be modified. However, it should be appreciated that if the contact status of an electrode could be modified to indicate a lower level of contact (e.g., from “in contact” to “no contact”), then all electrodes would need to be analyzed in step 608 taking into account the contact status of nearby electrodes.

[0036] In some embodiments, the decision to change the contact status of an electrode is based, at least in part, on the contact status of one or more neighboring electrodes. In some embodiments, one or more rules are applied for changing the contact status of a given electrode based on the contact status of one or more neighboring electrodes, as described in more detail with respect to FIGS. 7A-12B . In some embodiments, one or more additional inputs may be utilized, including, for example, the distance from the electrode being analyzed to one or more neighboring electrodes, the contact status of the neighboring electrodes (if the contact status includes more than a binary decision of "in contact" or "no contact"), the contact status of the electrode being analyzed (if the contact status includes more than a binary decision of "in contact" or "no contact"), and / or the contact status history of the electrode being analyzed and / or one or more neighboring electrodes.

[0037] In some embodiments, the contact status of an electrode is altered based on the contact status of nearby electrodes. The term nearby may refer to both electrodes adjacent to and not adjacent to the electrode being analyzed for alteration. In some embodiments, multiple electrodes are organized into subsets of electrodes called cliques, and an electrode may be a member of one or more cliques, which may be composed of both adjacent and non-adjacent electrodes. In some embodiments, the contact status of an electrode is altered based on the contact status of electrodes within the clique. For example, in some embodiments, each clique is composed of three electrodes that collectively define a plane. In some embodiments, the contact status of one of the electrodes within the clique may be altered from a "no contact" state to a "contact" state if the contact status of one or both of the other electrodes in the clique is determined to be "in contact" in step 606. As in the examples shown in FIGS. 7A-12B , various methods may be utilized to determine whether to alter the contact status of an electrode based on the contact status of one or more nearby electrodes, including, for example, one or more adjacent electrodes, one or more non-adjacent electrodes, and / or one or more electrodes included as part of a clique.

[0038] In some embodiments, changing the contact status of an electrode may include changing the contact status from "no contact" to "contact." In some embodiments, the contact status of an electrode may also be changed from "contact" to "no contact" based on the contact status of nearby electrodes. However, for ease of explanation, the contact status in the provided example is always changed from a lesser contact status to a more contact status. In some embodiments where multiple contact statuses are possible, the change in contact status may be based on a combination of the physical distance / proximity of nearby electrodes and the contact status of the nearby electrodes. For example, directly adjacent or more proximate electrodes may be given greater weight when changing the contact status of an electrode. For example, the contact status of an electrode located adjacent to two electrodes determined to be "in contact" in step 606 may be changed from a "no contact" contact status to a "in contact" contact status (regardless of the intermediate category of "intermittent contact"). In some embodiments, the contact status of an electrode located between two electrodes designated "in contact," but not immediately adjacent to one or more of those electrodes, may be changed from "no contact" to "intermittent contact" rather than changed to "in contact" as a result of the greater distance between the respective electrodes. In this example, the distance from the electrode or electrodes designated "in contact" is utilized along with the electrode's contact status to determine whether to change the contact status of a given electrode.

[0039] In some embodiments, a magnitude or value representing the contact status may be used as an input in determining whether to change the contact status. For example, in some embodiments, an electrode may be assigned more states than simply "in contact" and "no contact." In the simplest example, an electrode may also be assigned "intermittent contact," but other embodiments may include a variety of possible contact statuses. In still other embodiments, the actual values ​​of nearby electrodes and / or the electrode being analyzed may be used to determine the contact status (e.g., BECI values, other calculations used to determine the contact status). In these embodiments, the magnitude of the contact status associated with both nearby electrodes and the electrode being analyzed for change may be used in determining whether to change the contact status and what the contact status should be. For example, multiple nearby electrodes determined to be in very good contact with the tissue based on measured electrical characteristics may have a greater impact on the decision to change the contact status than multiple nearby electrodes determined to be in very good contact with the tissue based on measured electrical characteristics that indicate less confidence or certainty regarding contact. Similarly, the contact status (e.g., a magnitude or value representing the contact status) of the electrode being analyzed for change may be used as an input in determining whether to change the contact status. For example, in the simplest case, the change in contact state may be limited to a single step (e.g., from "no contact" to "intermittent contact" or from "intermittent contact" to "contact"), In other embodiments, the change in contact state may be based on a combination of the contact state of the electrode being analyzed and the contact states of nearby electrodes.

[0040] In this manner, an electrode that is assigned an initial contact state (e.g., "no contact") in step 606 based on its measured electrical characteristics may have its contact state changed in step 608 based on the contact states of nearby electrodes.

[0041] Specific examples of rules that may be applied to change the contact status of an electrode are described below with reference to FIGS. 7A-11B. These examples assume that measured electrical characteristics are used to assign a binary contact status (e.g., "in contact" or "out of contact") to each electrode, and that the contact status is simply changed from "out of contact" to "in contact." It should be understood that in other embodiments, various other factors described above may be used in combination with these rules to determine whether to change the contact status of a given electrode. For ease of explanation, a grid-like electrode array having 16 electrodes, similar to that shown in FIG. 3, is used as an example. It should be understood that the principles discussed herein may also be applied to electrodes in other configurations.

[0042] FIG. 7A illustrates a 4x4 grid of a grid catheter similar to catheter 300 of FIG. 3 with 16 electrodes. Alpha-numeric labels are used for the electrodes here for ease of illustration. The initial determination of the contact status of the electrodes within the grid (step 606 of FIG. 6) is shown in FIG. 7A based on one or more measured electrical properties. For simplicity, electrode states indicated by open circles are not relevant to the analysis and can be ignored (or assigned a no-contact value), gray circles represent electrodes determined to be "no-contact" based on the measured electrical properties, and black circles represent electrodes in a "contact" state based on the measured electrical properties. FIG. 7B illustrates the modified state of the electrodes (step 608 of FIG. 6), with black circles utilized to indicate "in contact."

[0043] As shown in FIG. 7A, electrodes A1, C1, C2, D2, A4, and D4 were determined to be “in contact” based on their measured electrical properties, while electrodes B1, B3, and D3 were assigned a “no contact” status based on their measured electrical properties.

[0044] In the example shown in Figures 7A and 7B, a rule is applied that an electrode's contact status can be changed from "no contact" to "in contact" if it is located between any electrode pairs determined to be "in contact." As shown in Figures 7A and 7B, electrode B1 is changed from "no contact" (gray in Figure 7A) to "in contact" (black in Figure 7B) based on electrodes A1 and C1 being "in contact." Similarly, electrode B3 is changed based on electrodes C2 and A4 being "in contact," and electrode D3 is changed based on electrodes D2 and D4 being "in contact." In some embodiments, the output presented to the technician via the display is based on the contact status shown in Figure 7B.

[0045] In the particular example described above and shown in FIGS. 7A and 7B, the electrode pairs determined to be "in contact" are separated by only one electrode, which is the electrode that can be changed from "not in contact" to "in contact." In some embodiments, the electrode pairs may be separated by multiple electrodes, and each electrode between the electrode pairs can be changed based on the electrode pair. For example, if A1 and A4 are "in contact," then one or both of A2 and A3 can be changed from "not in contact" to "in contact." Similarly, if A1 and D4 are "in contact," then one or both of B2 and C3 can be changed from "not in contact" to "in contact."

[0046] Figures 8A and 8B illustrate electrode state changes based on the contact status of electrodes located within a 2x2 clique. As shown in Figure 8A, electrodes A1, B2, C3, and C4 were determined to be "in contact" based on their measured electrical characteristics. Electrodes A2, B1, D3, and D4 were determined to be "out of contact" based on their measured electrical characteristics. In this example, electrodes are organized into four-electrode cliques that form a square. The rule applied is that if two or more electrodes within a given clique (e.g., a 2x2 square) are identified as "in contact" based on their measured characteristics, the contact status of the other two electrodes within the square may be changed to "in contact." As shown in Figure 8B, electrodes A2 and B1 are inverted or changed to "in contact" based on the contact status of electrodes A1 and B2. Similarly, electrodes D3 and D4 are inverted from "out of contact" to "in contact" based on the contact status of electrodes C3 and C4. In this example, it doesn't matter which electrodes in a group or clique of electrodes are "in contact," as long as two of the four electrodes (in this example) indicate "in contact," and the other two can be flipped from "no contact" to "in contact."

[0047] 9A and 9B illustrate an example in which contact status is changed when an electrode is located adjacent (horizontally and vertically) to an electrode determined to be "in contact" with tissue. In this example, electrode B2 was determined to be "in contact" based on measured electrical properties (as shown in FIG. 9A). Applying the rule that contact status can be changed when an electrode is located adjacent (horizontally and vertically) to an electrode in contact, electrodes B1, A2, C2, and B3 located adjacent to electrode B2 are changed from "no contact" to "in contact," as shown in FIG. 9B. In some embodiments, the contact status shown in FIG. 9B is displayed to the user or technician.

[0048] 10A and 10B show a similar example in which the contact status is changed when an electrode is located adjacent (horizontally, vertically, or diagonally) to an electrode determined to be "in contact" with tissue. In this example, electrode B2 (as shown in FIG. 10A) is again determined to be "in contact" based on its measured electrical properties. Applying the rule that the contact status is changed when an electrode is located adjacent (vertically, horizontally, or diagonally) to an electrode in contact, electrodes A1, B1, C1, A2, C2, A3, B3, and C3 located adjacent to electrode B2 are changed from "no contact" to "in contact," as shown in FIG. 10B. In some embodiments, the contact status shown in FIG. 10B is displayed to the user or technician.

[0049] 11A and 11B illustrate an example in which the contact status is changed when electrodes are located within a rectangle (or other shape) defined by electrodes determined to be "in contact." For example, in the embodiment shown in FIG. 11A, electrodes A1, C1, A4, and C4 are determined to be in contact based on measured electrical characteristics. Electrodes B1, A2, B2, C2, A3, B3, C3, and B4 are determined to be not in contact based on measured electrical characteristics. Electrodes A1, C1, A4, and C4 form a rectangle. In this example, application of the rule changes the contact status of electrodes B1, A2, B2, C2, A3, B3, C3, and B4 to "in contact," as shown in FIG. 11B, because they are located within the rectangle defined by electrodes A1, C1, A4, and C4. In this example, some of the electrodes are located between electrodes determined to be in contact (e.g., electrode B1 is located between "in contact" electrodes A1 and C1). Other electrodes, such as electrodes A2 and A3, are only adjacent to one other electrode determined to be "in contact." In this example, electrodes A2 and A3 are modified to indicate contact because they are within the rectangle defined by electrodes A1, C1, A4, and C4, even though they are only directly adjacent to one other "in contact" electrode. In some embodiments, the contact status shown in FIG. 11B is displayed to the user or technician.

[0050] 7A through 11B, a 4x4 grid (16 electrodes) is used as an example. It is recognized that catheters with more or fewer electrodes can still utilize the methods described herein for defining cliques and modifying the contact status of one or more electrodes based on the contact status of other electrodes in the same clique. In other examples, the grid may be larger or smaller. The grid need not be square. Other sized grids include, but are not limited to, 2x3, 3x2, 3x3, 3x4, 4x3, 4x5, 5x4, or 5x5.

[0051] In some examples, a nearby electrode, as defined herein, is not necessarily an adjacent electrode. A non-adjacent electrode can be defined as a nearby electrode if it is in the same clique as the electrode of interest. As an example, FIG. 12A shows a 5×4 grid in which each of the outer corner electrodes (e.g., electrodes A1, D1, A5, and D5) has been determined to be in "contact" based on measured electrical characteristics. Applying the same rule as in FIGS. 11A and 11B, any electrode located within the rectangle defined by the corners of the rectangle containing the electrodes determined to be in "contact" can be changed to a "contacting" state. Applying that rule to the example shown in FIG. 12A would change all electrodes to a "contacting" state, including those that are not adjacent to any of the electrodes initially determined to be in "contact." For example, electrodes A3 and D3 are not directly adjacent to any of the electrodes initially determined to be in "contact."

[0052] The examples shown in Figures 7A through 12B are merely illustrative of the types of rules that may be applied to alter the state of one or more electrodes based on the contact state of one or more nearby electrodes. Various other types of rules may be applied, either alone or in combination with other rules, depending on the application. Furthermore, while the examples shown in Figures 7A through 12B were based on only two contact states (i.e., "in contact" and "no contact"), in other embodiments, additional contact states may exist, and these contact states may be used as inputs for determining whether to alter the contact state of one or more nearby electrodes. Similarly, the contact state (if not binary) of the electrode being analyzed may also be used as an input for determining the altered contact state of the electrode.

[0053] While the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope of the appended claims.

[0054] Consideration of possible embodiments. The following is a non-exclusive description of possible embodiments of the present invention.

[0055] According to one aspect, a method for altering a contact state of one or more electrodes in a plurality of electrodes disposed on a medical device includes measuring an electrical characteristic of each electrode in the plurality of electrodes disposed on the medical device, determining a contact state of each electrode in the plurality of electrodes based on the measured electrical characteristic of the corresponding electrode, and altering the contact state of a first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes.

[0056] The method of the preceding paragraph may additionally and / or alternatively optionally include any one or more of the following features, steps, configurations, and / or additional components.

[0057] For example, the step of measuring the electrical property may include measuring bipolar electrode complex impedance (BECI).

[0058] The contact state may comprise a "no contact" state and a "contact" state.

[0059] The contact states may include a "no contact" state, an "intermittent contact" state, and a "contact" state.

[0060] The step of changing the contact state of a first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes may include changing the contact state of the first electrode from a "no contact" state to a "contact" state based on at least one adjacent electrode that has been assigned a "contact" state based on the measured electrical characteristics.

[0061] The step of changing the contact state of a first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes may include changing the contact state of the first electrode from a “no contact” state to a “contact” state based on an electrode pair located opposite the first electrode being assigned a “contact” state based on measured electrical characteristics.

[0062] The step of changing the contact state of a first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes may include changing the contact state of the first electrode from a "no contact" state to a "contact" state if any of the adjacent electrodes is assigned a "contact" state based on the measured electrical characteristics.

[0063] According to another aspect, a method for altering a contact state of one or more electrodes in a plurality of electrodes disposed on a medical device includes measuring electrical characteristics of each electrode in the plurality of electrodes disposed on a medical device, determining a contact state of each electrode in the plurality of electrodes based on the measured electrical characteristics of the corresponding electrode, the contact state including "in contact," "intermittent contact," and "no contact," and altering the contact state of one or more electrodes in the plurality of electrodes based on one or more nearby electrodes having a contact state of "in contact."

[0064] The method of the preceding paragraph may optionally additionally and / or alternatively include one or more of the following features, steps, configurations, and / or additional components.

[0065] For example, the step of changing the contact status of one or more electrodes may include at least one of changing the contact status of one or more electrodes from "no contact" to "contact" and changing the contact status of one or more electrodes from "intermittent contact" to "contact."

[0066] The measured electrical property may include bipolar electrode complex impedance (BECI).

[0067] The one or more adjacent electrodes may include an electrode pair separated by one or more electrodes.

[0068] The one or more nearby electrodes may include nearest neighbor electrodes in a horizontal, vertical, or diagonal direction.

[0069] The one or more adjacent electrodes may include four electrodes forming a rectangle separated by one or more electrodes.

[0070] According to another aspect, a system for use with a medical device having multiple electrodes and configured to be inserted into a patient includes a signal generator configured to apply multiple drive signals across different electrode pairs of the medical device; a measurement circuit configured to measure responses of the multiple electrodes to the drive signals and generate an impedance value for each of the multiple electrodes of the medical device; and a contact assessment module configured to determine, for each electrode, a contact status of each of the multiple electrodes based on the generated impedance value associated with each electrode, wherein the contact assessment module is further configured to alter the contact status of one or more of the multiple electrodes based at least in part on the contact status of one or more nearby electrodes.

[0071] The system of the preceding paragraph may optionally additionally and / or alternatively include one or more of the following features, steps, configurations, and / or additional components.

[0072] For example, the contact state determined by the contact assessment module for each electrode may include a "contact" state and a "no contact" state.

[0073] The contact status determined by the contact assessment module for each electrode may include a "contact" status, a "no contact" status, and an "intermittent contact" status.

[0074] Changing the contact status by the contact assessment module may include changing the contact status of at least one of the electrodes from a "no contact" state to a "contact" state based on at least one nearby electrode that has been assigned a "contact" state based on the measured electrical characteristics.

Claims

1. A method of operating a system for use with a medical device having a plurality of electrodes and configured for insertion into a patient, comprising: measuring an electrical characteristic of each electrode in the plurality of electrodes disposed on the medical device; determining a contact status of each electrode in the plurality of electrodes based on the measured electrical characteristic of the corresponding electrode, the contact status being indicative of contact with adjacent tissue; and changing the contact state of the first electrode based on a combination of the physical distance / proximity of one or more other electrodes in the plurality of electrodes to a first electrode in the plurality of electrodes and the determined contact state of the one or more other electrodes.

2. The method of claim 1 , wherein measuring the electrical property comprises measuring bipolar electrode complex impedance (BECI).

3. 2. The method of claim 1, wherein the contact state comprises a "no contact" state and a "contact" state, the "no contact" state indicating that the electrode is not in contact with the adjacent tissue, and the "contact" state indicating that the electrode is in contact with the adjacent tissue.

4. The method of claim 1 , wherein the contact states comprise a "no contact" state, an "intermittent contact" state, and a "contact" state.

5. 2. The method of claim 1, wherein changing the contact state of the first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes comprises changing the contact state of the first electrode from a "no contact" state to a "contact" state based on at least one adjacent electrode that has been assigned a "contact" state based on the measured electrical characteristic.

6. 2. The method of claim 1, wherein changing the contact state of the first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes comprises changing the contact state of the first electrode from a "no contact" state to a "contact" state based on an electrode pair separated by one or more electrodes including the first electrode being assigned a "contact" state based on the measured electrical characteristic.

7. 2. The method of claim 1, wherein changing the contact state of the first electrode in the plurality of electrodes based on the determined contact state of one or more other electrodes in the plurality of electrodes comprises changing the contact state of the first electrode from a "no contact" state to a "contact" state when the first electrode is part of a rectangular structure of electrodes and four electrodes at each corner of the rectangular structure are each assigned a "contact" state based on the measured electrical characteristics.

8. A method of operating a system for use with a medical device having a plurality of electrodes and configured for insertion into a patient, comprising: measuring an electrical characteristic of each electrode in the plurality of electrodes disposed on the medical device; determining a tissue contact state of each electrode in the plurality of electrodes based on the measured electrical characteristics of the corresponding electrode, the tissue contact state comprising "in contact," "intermittent contact," and "no contact"; and changing the tissue contact state of one or more electrodes in the plurality of electrodes based on one or more nearby electrodes having the tissue contact state "in contact", the nearby electrodes being selected based on their distance to the one or more electrodes in the plurality of electrodes.

9. 9. The method of claim 8, wherein changing the tissue contact state of one or more electrodes comprises at least one of changing the tissue contact state of the one or more electrodes from "no contact" to "in contact" and changing the tissue contact state of the one or more electrodes from "intermittent contact" to "in contact."

10. The method of claim 8 , wherein the measured electrical property comprises bipolar electrode complex impedance (BECI).

11. The method of claim 8 , wherein the one or more adjacent electrodes comprises an electrode pair separated by one or more electrodes.

12. The method of claim 8 , wherein the one or more nearby electrodes include nearest neighbor electrodes in a horizontal, vertical, or diagonal direction.

13. The method of claim 8 , wherein the one or more adjacent electrodes are four electrodes forming a rectangle separated by one or more electrodes.

14. 1. A system for use with a medical device having a plurality of electrodes and configured for insertion into a patient, comprising: a signal generator configured to apply a plurality of drive signals across different electrode pairs of the medical device; a measurement circuit configured to measure a response of the plurality of electrodes to the drive signal and generate an impedance value for each of the plurality of electrodes of the medical device; a contact assessment module configured to determine, for each electrode, a tissue contact state of each of the plurality of electrodes based on the generated impedance value associated with each electrode; The system, wherein the contact assessment module is further configured to modify the tissue contact state of one or more electrodes of the plurality of electrodes based at least in part on the tissue contact state of one or more nearby electrodes, and the nearby electrodes are configured to be selected based on a distance relative to the one or more electrodes of the plurality of electrodes.

15. The system of claim 14 , wherein the tissue contact state determined by the contact assessment module for each electrode includes a “contact” state and a “no contact” state.

16. 15. The system of claim 14, wherein the tissue contact state determined by the contact assessment module for each electrode includes a "contact" state, a "no contact" state, and an "intermittent contact" state.

17. 15. The system of claim 14, wherein the altering of the tissue contact state by the contact assessment module comprises changing the tissue contact state of at least one of the electrodes from a "no contact" state to a "contact" state based on at least one nearby electrode that has been assigned a "contact" state based on measured electrical characteristics.

18. The method described in claim 1, wherein the physical distance / proximity of one or more other electrodes to the first electrode is limited to one or more other electrodes located adjacent to the first electrode.

19. The method described in claim 8, wherein the one or more nearby electrodes selected based on their distance to the one or more electrodes are limited to nearby electrodes located adjacent to the one or more electrodes.

20. The system described in claim 14, wherein the nearby electrodes are limited to nearby electrodes located adjacent to the one or more electrodes.

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