Expandable catheter fitting and orientation based on automated pulmonary vein anatomical characterization

Abstract

To provide methods based on a balloon catheter.SOLUTION: A method includes, using anatomical data, calculating multiple cross-sectional shapes of a lumen of an organ in a body of a patient at multiple respective positions on a medial axis of the lumen. One or more of the positions on the medial axis are identified, at which a given expandable frame of a catheter should fit the cross-sectional shapes. The one or more identified positions are presented to a user.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to medical probes and, more particularly, to methods for using balloon catheters. [Background technology]

[0002] Various methods for estimating the cross-sectional geometry of a lumen to facilitate catheter-based procedures have been reported in the patent literature. For example, U.S. Patent Application Publication No. 2009 / 0182287 describes an apparatus, system, and method for locating intraluminal structures and medical devices during non-surgical medical techniques, such as cardiac ablation, by determining the intraluminal conductance and / or cross-sectional area at multiple locations within a body lumen. In one embodiment, as a clinician manipulates a balloon catheter, the manipulation reflects the changing electrical conductance of the lumen, and therefore its changing cross-sectional area, relative to the balloon catheter.

[0003] As another example, U.S. Patent No. 10,096,105 describes a method and system for automatically locating target therapeutic structures, such as pulmonary vein ostia, from anatomical images. The method includes calculating the most likely path of blood flow through the pulmonary veins based on a cross-sectional area minimization technique and calculating pulmonary vein geometry as a function of length. For example, the pulmonary vein ostia can be located by analyzing changes in pulmonary vein dimensional size or other anatomical factors, such as absolute size. The method can include determining multiple centroids along the length of the pulmonary vein. The method can be an algorithm executed by a processing unit of a navigation system or other component of a medical system.

[0004] U.S. Patent Application Publication No. 2019 / 0343578 describes an electrophysiology catheter that conforms to the shape of a pulmonary vein undergoing ablation therapy for cardiac arrhythmias, creating a consistent tissue ablation line along the length and circumference of the pulmonary vein tissue. During inflation, certain portions of the elliptical cross-sectional shape of the pulmonary vein may be overstressed, preventing other portions of the pulmonary vein from contacting the ablation balloon and limiting the effectiveness of the ablation therapy. Accordingly, aspects of the present disclosure are directed to an ablation balloon having a substantially elliptical shape. Summary of the Invention [Means for solving the problem]

[0005] One embodiment of the present invention, described below, provides a method that includes using anatomical data to calculate multiple cross-sectional shapes of a lumen of an organ within a patient's body at multiple respective positions on the medial axis of the lumen. One or more positions on the medial axis at which a given expandable frame of a catheter would conform to the cross-sectional shape are identified. The one or more identified positions are presented to a user.

[0006] In some embodiments, the one or more identified locations include a range of adjacent locations on the medial axis of the lumen.

[0007] In some embodiments, the calculated cross-sectional shape is perpendicular to the medial axis at each location, while in other embodiments, the cross-sectional shape is an ellipse.

[0008] In one embodiment, identifying the locations includes fitting the cross-sectional shape to a respective ellipse and identifying one or more locations where the ellipse has an elliptical index greater than a predetermined value, the elliptical index being defined as a maximum for a circle.

[0009] In some embodiments, the method further includes presenting to the user an indication of the diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen for at least one of the identified locations.

[0010] In one embodiment, indicating the identified locations includes marking one or more identified locations on a median cross-sectional view of the lumen.

[0011] In another embodiment, the lumen is a pulmonary vein (PV), and identifying the location includes identifying one or more locations where a given expandable frame of the catheter will completely occlude the PV.

[0012] In some embodiments, the method further includes identifying respective directions in which a given expandable frame of the catheter will conform to the cross-sectional shape at one or more of the locations.

[0013] In some embodiments, the lumen is a pulmonary vein (PV), and identifying the respective direction includes identifying the respective direction in which a given expandable frame of the catheter would completely occlude the PV.

[0014] In one embodiment, the method further includes using a graphical tool to indicate to the user that a given expandable frame orientation is angularly aligned, within a pre-specified tolerance, with a tangent to the medial axis of the lumen at one or more of the locations.

[0015] In another embodiment, indicating that a given expandable frame is angularly aligned includes recoloring a display of electrodes disposed on the expandable frame of the catheter.

[0016] According to another embodiment of the present invention, there is further provided a system including a memory and a processor, wherein the memory is configured to store anatomical data of a lumen of an organ within a patient's body, and the processor is configured to (a) calculate, based on the anatomical data, multiple cross-sectional shapes of the lumen at multiple respective positions on a medial axis of the lumen, (b) identify one or more positions on the medial axis where a given expandable frame of the catheter will conform to the cross-sectional shapes, and (c) present the one or more identified positions to a user.

[0017] The present invention will be more fully understood from the following detailed description taken in conjunction with the drawings, in which: [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic, pictorial illustration of a balloon catheter-based ablation system, in accordance with one embodiment of the present invention; [Figure 2] 1 is a schematic illustration of variable cross-sectional ellipse of the pulmonary vein (PV) anatomy, in accordance with an embodiment of the present invention; FIG. [Figure 3] 3 is a graph of the ellipticity index and mean diameter of the PV of FIG. 2 along the medial axis of the PV, in accordance with one embodiment of the present invention. [Figure 4] 1 is a flow chart that schematically illustrates a method for estimating suitability and best location in a pulmonary vein (PV) for performing single-shot balloon ablation, in accordance with an embodiment of the present invention. [Figure 5] 2 is a schematic, pictorial illustration of a graphical user interface configured to visually display a proposed orientation of the balloon catheter of FIG. 1 at a proposed PV center location, in accordance with an embodiment of the present invention. FIG. [Figure 6] FIG. 2 is a schematic, pictorial illustration of a graphical user interface configured to visually indicate a preferred orientation of the balloon catheter of FIG. 1 by graphically displaying primed electrodes, in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Overview Various medical conditions involving a body lumen, such as drug-resistant atrial fibrillation (AF), can be treated with an expandable catheter having the general configuration of an oval surface on at least a portion of the expandable frame of the catheter relative to the longitudinal axis of the catheter.

[0020] For example, the lumen can be treated by ablation or dilation of a balloon catheter, or by another type of expandable catheter for ablation, such as a basket catheter.

[0021] In a typical AF balloon ablation procedure, the distal end of a balloon-fitted catheter equipped with an ablation element (e.g., an electrode) is inserted into the pulmonary vein (PV) ostium to ablate arrhythmogenic tissue in the PV ostium. To efficiently and safely isolate the arrhythmia, the entire circumference of the ostium should be ablated, preferably simultaneously (i.e., in a "single shot").

[0022] When ablating PVs with balloon ablation catheters, results show that the success rate of single-shot ablation is highly correlated with the anatomical characterization of the treated PV. For example, narrow PVs or fairly long, oval PVs typically have lower success rates than larger, rounder PVs due to lower occlusion of the PV by the balloon. To date, ablation can be optimized primarily based on the operator's expertise and / or verification of occlusion with additional modalities (e.g., fluoroscopy).

[0023] Embodiments of the invention described below use a processor to determine preferred locations (e.g., regions) along the medial axis for placing an expandable catheter, e.g., an inflatable ablation balloon catheter, with reference to the mean diameter of the lumen (e.g., for the PV mean diameter, the curve in FIG. 3 ). In some embodiments, the processor further determines a preferred orientation of the expandable catheter at each preferred location. Embodiments use pre-acquired anatomical data of the lumen, such as an anatomical map of the PV, based on which the processor calculates the medial axis of the PV and then calculates multiple cross-sectional shapes of the lumen (e.g., the PV) at multiple respective locations along the medial axis. In one embodiment, the calculated cross-sectional shapes are orthogonal to the medial axis at each location.

[0024] From the cross-section, the processor then identifies (e.g., estimates) one or more locations (e.g., a range of locations) where a given expandable frame of the catheter will fit the cross-sectional shape. For example, the processor may identify a location where a particular balloon will best fit to occlude the lumen. In one embodiment, the one or more identified locations include a range of adjacent locations on the medial axis of the lumen. The processor typically presents the one or more identified locations to the user.

[0025] The processor may, for example, estimate the ellipse of the cross section of the PV that a balloon with a particular equatorial diameter would best fit. For example, in the case of single-shot ablation, the processor may prefer inner locations where the ellipse of the lumen is closer to a circle, and exclude central locations where the ellipse of the long PV cross section is greater.

[0026] In some embodiments, the processor calculates the ellipticity index as a function of the medial axis position and uses the ellipticity index to determine the optimal PV region in which to position a balloon of a given equatorial diameter. For example, in one embodiment, the processor determines that PV regions with an ellipticity index above a certain threshold (the ellipticity index defined as the maximum for a circular cross-section) are suitable for single-shot balloon ablation. The processor then compares the average diameter of PVs in those regions with the diameters of available balloons to determine whether suitable balloons exist that can perform single-shot ablation. Alternatively, the processor may determine that only segmented (e.g., piecewise) ablation can be performed to ablate the entire circumference of the PV.

[0027] In some embodiments, the processor is further configured to present to the user, for at least one of the identified locations, an indication of the diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen. In one embodiment, the processor is configured to present the identified locations by marking one or more identified locations on an intermediate cross-sectional view of the lumen.

[0028] In one embodiment, the processor colors the map of the PVs to display the best-fit region. In one embodiment, the color of the region is selected according to the elliptical index that exceeds a predetermined threshold. In another embodiment, color codes are used to reflect different values ​​of the elliptical index along the medial axis. Thus, the colored display assists the operator in determining whether and where a single-shot balloon ablation procedure can be performed across the PV medial location.

[0029] In yet another embodiment, the processor estimates the quality of the fit (e.g., best fit) of the balloon to the PV anatomy using additional criteria such as ellipticity index (e.g., using a metric to determine whether the fit is very good, good, fair, or poor). For example, a best fit method may be used that requires a PV with a large enough ellipticity index at the PV location, as well as a balloon equatorial diameter that provides an area equal to the PV cross-sectional area. Using such requirements, the processor can find the best medial axis position that minimizes the difference between the circumference of the PV and the equatorial circumference of the balloon, where such difference depends on the ellipticity index, as described below.

[0030] In some embodiments, the processor calculates a tangent to the median curve at the preferred locations to be used as the preferred orientation of the expandable frame of the catheter at each location.

[0031] In some embodiments, the position and orientation of the catheter's expandable frame is tracked during the interventional procedure, and the user receives an indication on the anatomical map of how accurately the catheter is positioned and oriented. To this end, the processor compares the tracked orientation of the frame's longitudinal axis with a tangent to the median at that position and indicates whether the frame is angularly aligned with the tangent within a pre-specified angular tolerance.

[0032] The electrodes are typically radially positioned on a frame (e.g., a balloon membrane) such that the frame is properly angularly aligned with the longitudinal axis, directing the catheter in a symmetrical direction relative to the anatomy, resulting in more electrodes making firm contact. In one embodiment, the processor indicates the degree of directional accuracy of the catheter by graphically indicating (e.g., coloring) the progressive number of electrodes on the catheter that are in contact with tissue. When all of the electrodes are colored (e.g., angular alignment is deemed acceptable), the user knows the catheter is sufficiently directionally aligned relative to the anatomy to perform its function (e.g., balloon ablation of the PV ostium).

[0033] Available balloon diameters for PV ablation range from approximately 15 to 30 millimeters, and the processor identifies and selects the most suitable balloon diameter while checking for the best fit. As noted above, more rarely, the processor may determine that single-shot balloon ablation of the PV is not possible because both regions of the PV are sufficiently circular and sized to accommodate balloons of available diameters. In the latter case, as suggested above, the physician may select a suitable balloon to perform segmented ablation (i.e., multi-shot ablation).

[0034] Typically, the processor is programmed with software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions outlined above.

[0035] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable any person skilled in the art to make and use the invention and will describe several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently contemplated to be the best mode of carrying out the invention.

[0036] As used herein, the term "about" or "approximately" in reference to any numerical value or range of values ​​indicates a suitable dimensional tolerance that allows a portion of a component or a collection of components to function for the intended purpose described herein. More specifically, the term "about" or "approximately" can indicate a range of values ​​of ±10% of the stated value; for example, "about 90%" can indicate a range of values ​​of 81% to 99%. Furthermore, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject, and are not intended to limit the use of the above-described systems or methods to humans, although use of the present invention in human patients represents a preferred embodiment. Additionally, the term "proximal" refers to a location closer to the operator, while "distal" refers to a location further from the operator or physician.

[0037] Although the disclosed embodiments describe an elliptical lumen cross-section, this method may be applied with other lumen cross-sectional shapes (e.g., a distorted circle) and with best-fitting non-circular balloons (e.g., a hemispheroid).

[0038] By estimating the PV region where a particular balloon is best positioned, and optionally estimating the best orientation of the balloon in the PV region, balloon therapy in general, and balloon ablation procedures in particular, can be made safer and more effective.

[0039] System Description 1 is a schematic, pictorial illustration of a catheter-based ablation system 20, in accordance with one embodiment of the present invention. System 20 comprises a catheter 21, with an ablation balloon 40 fitted to the distal end of a catheter shaft 22, as shown in inset 25, inserted by a physician 30 through a sheath 23 into the left atrium 45 of a heart 26 of a patient 28 lying on a table 29.

[0040] To reach a target location within the left atrium 45, designated as the ostium of a pulmonary vein (PV) 47, physician 30 navigates the distal end of shaft 22 by manipulating shaft 22 and / or deflection from sheath 23 using manipulator 32 near the proximal end of the catheter. Physician 30 then manipulates catheter 40 within the left atrium 45 using catheter handle 31 to access and contact the target PV 47 ostium tissue.

[0041] To navigate the balloon 40, electrical signals from the balloon's individual electrodes 44 are used in an electrical tracking subsystem and a method termed ACL (Advanced Current Location) that can be implemented in various medical applications, for example, in the CARTO™ system manufactured by Biosense-Webster. The ACL method allows for tracking the position and orientation of the catheter frame (e.g., the direction of the balloon catheter's longitudinal axis as seen in FIG. 5). Such a method is described, for example, in U.S. Pat. No. 8,456,182, the disclosure of which is incorporated herein by reference.

[0042] As mentioned above, the PV47 ostium may have an irregular cross-section (e.g., elliptical), and to achieve uniform single-shot balloon ablation, it is important to determine the correct midpoint along the ostial area to place the balloon where the ellipticity value is minimal.

[0043] The proximal end of catheter 21 connects to control console 24, which includes processor 41, typically a general-purpose computer. Processor 41 has suitable front-end and interface circuitry 38 for receiving signals from catheter 21, delivering therapy via catheter 21 within heart 26, and controlling other components of system 20. Processor 41 is programmed with software to perform the functions described herein. The software may be downloaded to the computer in electronic form, for example, over a network, or alternatively or additionally, may be provided and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory. In particular, processor 41 executes the dedicated algorithms disclosed herein, included in FIG. 4, which enable processor 41 to perform the steps of the present disclosure, as described further below.

[0044] 1 is chosen solely for purposes of conceptual clarity. The techniques of the present disclosure can be similarly applied using other system components and settings. For example, system 20 may include other components and perform non-cardiac procedures.

[0045] Ablation balloon matching based on automated pulmonary vein anatomical characterization FIG. 2 is a schematic diagram of a variable cross-sectional ellipse of the pulmonary vein (PV) 47 anatomy, in accordance with one embodiment of the present invention. As can be seen, at the medial axis position (a), where the left atrium 45 and the PV 47 ostium approximately join, the shape of the PV cross section 56 is elliptical and fairly elongated, e.g., an oval with its major axis v significantly larger than its minor axis u. As can be further seen, around the medial axis position 62 between medial positions (b) and (c), the shape of the PV cross section 58 is approximately circular, and at medial axis position (d), the cross section 60 is again elliptical. As used herein, the term "medial axis" is used to refer to one or more centerlines (or central curves) of a surface that defines the lumen of an organ, such as the pulmonary veins to the left atrium. In this context, the term "medial axis" may also be referred to as "centerline" or "medial."

[0046] The degree of ellipticity can be defined in various ways. This specification provides two useful definitions:

[0047] The first elliptic index, O-index1, is

[0048]

number

[0049] As can be seen, the circle (with v=u) has O-index1=100.

[0050] A slightly elongated ellipse (e.g., v=1.25 u) has an O-index=80, and a fairly elongated ellipse (e.g., v=2 u) has an O-index=50.

[0051] Another definition of the elliptic index is based on the ratio η,

[0052]

number

[0053] and the elliptic index using η, O-index2, is

[0054]

number

[0055] The two definitions of ellipticity index are nearly identical (e.g., differ by a small percentage) for O-index values ​​above 80 and are similar for most practical purposes, e.g., do not differ by more than 10% for O-indexes above 60. Therefore, choosing which O-index to use may depend on other considerations, such as the best fit method used using O-index2, as described below. However, for extreme ellipticity values ​​(e.g., when v ≥ 3u; η ≥ 0.5), O-index1 should be used.

[0056] Here, a further useful measurement of the PV is defined, which is the mean diameter of the PV at a given intermediate position, where the mean diameter is (v+u). As can be seen, the mean diameter of a circular cross-section PV is the circular diameter of the circular cross-section PV. Another definition of mean diameter is:

[0057]

number

[0058] Given the ellipticity index and mean diameter of the PVs as a function of the medial axis position of PV 47, as shown in Figure 3 below, a processor such as processor 41 can identify the best region on the medial axis for placing an ablation balloon of a given diameter. The processor can also determine that single-shot balloon ablation of PV 47 is not feasible, for example, if the region of PV 47 is not sufficiently circular. Single-shot ablation can also be deemed not feasible if a balloon size is not available for any region deemed sufficiently circular, either because the lumen diameter is too small or too large for the balloon.

[0059] Figure 3 is a graph of the ellipticity index and mean diameter of PV 47 of Figure 2 along the medial axis 55 of PV 47, in accordance with one embodiment of the present invention. As can be seen in the bottom graph of Figure 3, in the medial axis region between medial axis positions (b) and (c), the ellipticity index (O-index2), referred to in the graph as the "PV O-index" of PV 47 (e.g., as calculated by processor 41), exceeds a value of 80, which in one embodiment is set as a lower threshold for the best fit criterion, essentially making the region suitable for balloon placement.

[0060] The top graph of Figure 3 shows that the mean diameter calculated as a function of medial axis position ranges from 15 to 25 mm in ellipticity for the region eligible for balloon treatment, i.e., between medial positions (b) and (c).

[0061] Because balloon diameters of 15 to 25 millimeters are typically available, the physician is informed by the system that such a balloon (e.g., a balloon with a diameter of approximately 20 mm) can be used to perform a single-shot ablation of PV47 in the region (b)-(c) of PV47.

[0062] As further seen in Figure 2, once the medial axis position 62 is determined, the processor 41 calculates a tangent 202 to the medial curve at that position. In some embodiments, this tangent is used as the target (e.g., proposed) direction for the balloon 40, as described in Figure 5. By extension, tangents can be calculated for a range of medial positions around the medial axis position 62, and each position deemed sufficiently suitable for placing an ablation balloon of a given diameter is also associated with a respective proposed direction for the balloon catheter.

[0063] Best fit of balloon using area-perimeter based metric As mentioned above, in another embodiment, the processor uses metrics above the ellipse index to estimate the quality of the fit of the balloon to the anatomy. Additional metrics may be more sophisticated than the ellipse index. For example, using such metrics, the processor may determine whether the fit is very good, good, fair, or poor. In one embodiment, a best fit criterion is provided that requires the equatorial diameter of the balloon, giving an area equal to the cross-sectional area of ​​the PV ellipse.

[0064] Using an additional metric, the processor can find the best medial axis position that minimizes the difference between the circumference of the PV and the equatorial circumference of the balloon, with such difference depending on the ellipticity index.

[0065] To define the above metric, we can write the circumference of an ellipse with area πuv and η>0, respectively, which (as derived by mathematician Zafary in 2009)

[0066]

number

[0067] By requiring the same balloon cross-sectional area, the balloon equatorial diameter D,

[0068]

number

[0069]

number

[0070] For all η>0, L E >L B and we can define metrics like:

[0071]

number

[0072] Combining requirements on balloon diameter and ellipticity index (e.g., as defined in Equation 2) above a given threshold while simultaneously minimizing a metric (such as the metric F(u,v) defined in Equation 3) can provide a flexible tool for determining the appropriateness and availability of balloon treatment for a given PV.

[0073] The above best fit method is given as an example, and other methods may be used, such as methods that require the same PV circumference and equatorial circumference of the balloon and minimize the difference between the respective areas covered by embodiments of the present invention.

[0074] Selection of ablation balloons for PV 4 is a flow chart that schematically illustrates a method for estimating the suitability and best location in a pulmonary vein (PV) 47 for performing single-shot balloon ablation, in accordance with an embodiment of the present invention. The algorithm, according to the presented embodiment, implements a process that begins by receiving a pre-acquired anatomical map of the PV 47 in a receive anatomical data step 70. The pre-acquired anatomical map may be uploaded by the processor 47 from the memory 33 of the system 20.

[0075] In a cross section calculation step 72, processor 40 calculates the elliptical cross sections of the PVs through the PV locations on medial axis 55, as illustrated in FIG.

[0076] Next, in ellipse index calculation 74, processor 40 calculates the ellipse index using one of the above definitions. The ellipse index can later be plotted as a function of the intermediate position as shown in FIG.

[0077] In an ellipse estimation step 76, processor 40 determines whether any of the intermediate positions have an ellipse index above a predetermined threshold, such that the ellipse value is low enough to be close to the magnitude of a circle's zero ellipse value.

[0078] If no location with a sufficiently low ellipse value is found, then processor 40 notifies physician 30 (e.g., on the display of system 20) in notification step 78 that a single-shot balloon ablation procedure is not possible for PV 47.

[0079] In a balloon equatorial diameter calculation step 80, processor 40 calculates the best fit equatorial diameter at the locations found to meet the criteria of step 76. The processor may use Equation 3 or another best fit method to define the best fit.

[0080] In a logging step 82, processor 40 stores in memory 33 the PV locations that meet the criteria of step 76 and their respective best-fit balloon equatorial diameters.

[0081] In a balloon diameter verification step 84, processor 40 determines whether the best fit equatorial diameter, if any, is within the range of useful (eg, available) balloon diameters.

[0082] If the diameter is found to be unusable, processor 40 notifies physician 30 (eg, on a display of system 20) in a notification step 86 that a single-shot balloon ablation procedure is not possible for PV 47.

[0083] In a suggestion step 88, processor 40 suggests to physician 30 suitable locations and diameters that meet the criteria of steps 76 and 84, for example using a diagram such as that of FIG.

[0084] Based on step 88, physician 30 selects an ablation balloon to perform a single-shot ablation of PV 47 in ablation balloon selection step 90.

[0085] Proposed orientation of ablation balloons based on anatomical characterization 5 is a schematic, pictorial illustration of a graphical user interface configured to visually display to a user proposed orientations 504 of the balloon catheter 40 of FIG. 1 at respective proposed pulmonary vein (PV) center locations 502, in accordance with one embodiment of the present invention. The graphical user interface is executed by the processor 41.

[0086] 5 shows an anatomical map 500 of the left atrium 45 with the tracked position and orientation of the balloon 40 positioned inside the ostium of the PV 47. The tracked orientation of the balloon catheter 40 is given by the catheter's longitudinal axis 506, which is defined as the direction parallel to the distal end of the shaft 22.

[0087] Two other PVs 47 are shown with proposed balloon locations 502 (such as location 62 in FIG. 2) and respective directions 504 (such as direction 202 in FIG. 2) superimposed. During a procedure such as balloon ablation, a physician can use the tracking system to position the balloons at the proposed locations and respective directions to ablate the PVs.

[0088] In some embodiments, a robotic arm is used to place the balloon catheter, and a processor commands the movement of the arm to bring the catheter to a tracked position and orientation with a pre-specified tolerance to the proposed position and orientation.

[0089] The graphical application described in FIG. 6 can assist the physician in determining where the balloon is located (either manually by the physician or automatically by a robotic arm) and oriented as needed.

[0090] GUI for best-aligned ablation balloon at selected pulmonary vein location 6 is a schematic, depiction of a graphical user interface configured to visually indicate the preferred orientation of the balloon catheter 40 of FIG. 1 by graphically displaying ready electrodes 44, in accordance with one embodiment of the present invention. As can be seen, the map shows the balloon 40 positioned inside the PV 47 with a calculated medial axis 55, and the catheter is visually indicated as being in the proper position and orientation by, for example, changing the balloon's color 605 (e.g., from blue to green), recoloring the radially disposed electrodes on the catheter's expandable frame (607), and / or underlining an increasing number of ablation-ready electrodes (606).

[0091] Text and / or audiovisual displays may also be provided.

[0092] Although the embodiments described herein relate primarily to pulmonary vein isolation procedures, the methods and systems described herein may also be used in other applications, such as ENT or neurology surgery.

[0093] It will therefore be understood that the above-described embodiments are cited by way of example, and that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description. Documents incorporated by reference into this patent application are to be considered an integral part of this application, except that if any term is defined in these incorporated documents in a way that contradicts the definition expressly or impliedly given herein, then only the definition in this specification shall be considered.

[0094] [Embodiment] (1) A method comprising: calculating a plurality of cross-sectional shapes of a lumen of an organ within a patient's body at a plurality of respective positions on a medial axis of the lumen using anatomical data; Identifying one or more of the locations on the intermediate shaft where a given expandable frame of a catheter will conform to the cross-sectional shape; and presenting the one or more identified locations to a user. (2) The method of embodiment 1, wherein the one or more identified locations include a range of adjacent locations on the medial axis of the lumen. (3) The method of claim 1, wherein the calculated cross-sectional shape is perpendicular to the intermediate axis at each of the locations. (4) The method of claim 1, wherein the cross-sectional shape is an ellipse. (5) The method of claim 4, wherein identifying the locations includes fitting the cross-sectional shape to a respective ellipse and identifying the one or more locations where the ellipse has an elliptical index greater than a predetermined value, the elliptical index being defined as a maximum for a circle.

[0095] (6) The method of embodiment 1, further comprising presenting to the user an indication of the diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen for at least one of the identified locations. (7) The method of embodiment 1, wherein presenting the identified locations includes marking the one or more identified locations on an intermediate cross-sectional view of the lumen. (8) The method of embodiment 1, wherein the lumen is a pulmonary vein (PV) and the identifying the location includes identifying the one or more locations where the given expandable frame of the catheter will completely occlude the PV. (9) The method of embodiment 1, comprising identifying respective orientations in which the given expandable frame of the catheter would conform to the cross-sectional shape at the one or more of the positions. (10) The method of embodiment 9, wherein the lumen is a pulmonary vein (PV) and identifying the respective directions includes identifying the respective directions in which the given expandable frame of the catheter would completely occlude the PV.

[0096] (11) The method of embodiment 9, further comprising using a graphical tool to indicate to the user that the orientation of the given expandable frame is angularly aligned, within a pre-specified tolerance, with a tangent to the medial axis of the lumen at the one or more of the positions. (12) The method of embodiment 11, wherein indicating that the given expandable frame is angularly aligned includes recoloring a display of an electrode disposed on the expandable frame of the catheter. (13) A system comprising: a memory configured to store anatomical data of a lumen of an organ within a patient's body; a processor, the processor comprising: calculating a plurality of cross-sectional shapes of the lumen at a plurality of respective positions on the medial axis of the lumen based on the anatomical data; Identifying one or more of the locations on the intermediate shaft where a given expandable frame of a catheter will conform to the cross-sectional shape; and The system is configured to present the one or more identified locations to a user. (14) The system of embodiment 13, wherein the one or more estimated positions comprise a range of adjacent positions on the medial axis of the lumen. (15) The system of claim 13, wherein the calculated cross-sectional shape is perpendicular to the medial axis at each of the locations.

[0097] (16) The system of embodiment 13, wherein the cross-sectional shape is an ellipse. (17) The system of embodiment 16, wherein the processor is configured to fit the cross-sectional shape to a respective ellipse and identify the one or more locations where the ellipse has an elliptical index greater than a predetermined value, the elliptical index being defined as a maximum for a circle. (18) The system of embodiment 13, wherein the processor is further configured to present to the user a display indicating a diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen for at least one of the identified locations. (19) The system of embodiment 13, wherein the processor is configured to present the identified locations by marking the one or more identified locations on an intermediate cross-sectional view of the lumen. (20) The system of embodiment 13, wherein the lumen is a pulmonary vein (PV), and the processor is configured to identify the location by identifying the one or more locations along the medial axis where the given expandable frame of the catheter will completely occlude the PV.

[0098] (21) The system of embodiment 13, wherein the processor is further configured to identify respective orientations in which the given expandable frame of the catheter would conform to the cross-sectional shape at the one or more of the positions along the intermediate axis. (22) The system of embodiment 21, wherein the lumen is a pulmonary vein (PV), and the processor is configured to identify the respective directions by identifying respective directions in which the given expandable frame of the catheter would completely occlude the PV. (23) The system of embodiment 13, wherein the processor is further configured to display to the user, using a graphical tool, that the orientation of the given expandable frame is angularly aligned, within a pre-specified tolerance, with a tangent to the medial axis of the lumen at the one or more of the positions. (24) The method of embodiment 23, wherein the processor is configured to indicate to the user that the given expandable frame is angularly aligned by recoloring the display of electrodes radially disposed on the expandable frame of the catheter.

Claims

1. 1. A system comprising: a memory configured to store anatomical data of a lumen of an organ within a patient's body; a processor, the processor comprising: calculating a plurality of cross-sectional shapes of the lumen at a plurality of positions on a medial axis of the lumen based on the anatomical data, the cross-sectional shapes being ellipses; fitting a plurality of said cross-sectional shapes to respective ellipses and calculating respective elliptic indices for each of said ellipses; Identifying one or more of the plurality of locations on the intermediate axis at which a given expandable frame of a catheter will conform to the cross-sectional shape based on the respective elliptical indices; and The system is configured to present the one or more identified locations to a user.

2. The system described in claim 1, wherein the one or more identified positions include a range of adjacent positions on the intermediate axis of the lumen.

3. The system of claim 1 , wherein the calculated cross-sectional shapes are orthogonal to the medial axis at the locations.

4. 2. The system of claim 1, wherein the processor is configured to identify the one or more locations where the ellipse has an elliptical index greater than a predetermined value, the elliptical index being defined as a maximum for a circle.

5. 10. The system of claim 1, wherein the processor is further configured to present to the user a display indicating a diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen for at least one of the identified one or more locations.

6. 2. The system of claim 1, wherein the processor is configured to present the identified one or more locations by marking the identified one or more locations on an intermediate cross-sectional view of the lumen.

7. 2. The system of claim 1, wherein the lumen is a pulmonary vein (PV), and the processor is configured to identify the one or more locations by identifying the one or more locations on the intermediate axis where the given expandable frame of the catheter will completely occlude the PV.

8. 2. The system of claim 1, wherein the processor is further configured to identify respective directions in which the given expandable frame of the catheter would conform to the cross-sectional shape at the one or more locations on the intermediate axis.

9. 9. The system of claim 8, wherein the lumen is a pulmonary vein (PV), and the processor is configured to identify each of the directions by identifying each direction in which the given expandable frame of the catheter would completely occlude the PV.

10. 10. The system of claim 1, wherein the processor is further configured to use a graphical tool to display to the user that the orientation of each of the given expandable frames is angularly aligned, within a pre-specified tolerance, with a tangent to the medial axis of the lumen at the one or more locations.

11. 11. The system of claim 10, wherein the processor is configured to indicate to the user that the given expandable frame is angularly aligned by recoloring a display of radially disposed electrodes on the given expandable frame of the catheter.

12. 1. A method comprising: using anatomical data to calculate a plurality of cross-sectional shapes of an ellipse of a lumen of an organ in a patient's body at a plurality of positions on a medial axis of the lumen; fitting a plurality of said cross-sectional shapes to respective ellipses and calculating respective elliptic indices for each of said ellipses; Identifying one or more of the plurality of positions on the intermediate axis at which a given expandable frame of a catheter will conform to the cross-sectional shape based on the respective elliptical indices; and presenting the one or more identified locations to a user.

13. The method described in claim 12, wherein the one or more identified positions include a range of adjacent positions on the intermediate axis of the lumen.

14. The method of claim 12 , wherein the calculated cross-sectional shapes are perpendicular to the medial axis at the locations.

15. 13. The method of claim 12, wherein identifying the one or more locations comprises identifying the one or more locations where the ellipse has an elliptical index greater than a predetermined value, the elliptical index being defined as a maximum for a circle.

16. The method of claim 12, further comprising presenting to the user an indication of the diameter of the expandable frame of the catheter that would fit the cross-sectional shape of the lumen for at least one of the one or more identified locations.

17. The method of claim 12, wherein presenting the identified one or more locations includes marking the identified one or more locations on an intermediate cross-sectional view of the lumen.

18. 13. The method of claim 12, wherein the lumen is a pulmonary vein (PV), and wherein identifying the one or more locations comprises identifying the one or more locations where the given expandable frame of the catheter will completely occlude the PV.

19. The method of claim 12, comprising identifying respective directions in which the given expandable frame of the catheter would conform to the cross-sectional shape at the one or more positions.

20. 20. The method of claim 19, wherein the lumen is a pulmonary vein (PV), and wherein identifying the respective directions comprises identifying respective directions in which the given expandable frame of the catheter would completely occlude the PV.

21. 20. The method of claim 19, further comprising using a graphical tool to indicate to the user that the respective orientation of the given expandable frame is angularly aligned, within a pre-specified tolerance, with a tangent to the medial axis of the lumen at the one or more locations.

22. 22. The method of claim 21, wherein indicating that the given expandable frame is angularly aligned includes recoloring a display of an electrode disposed on the given expandable frame of the catheter.

Images