Patent Description:
The present invention relates generally to medical devices, and particularly to methods and systems for mapping anatomical signals in a patient body and visualizing anatomical geometries in relation to probes.

A wide range of medical procedures involve placing objects, such as sensors, tubes, catheters, dispensing devices, and implants, within the body. In some systems, the graphical representations of anatomy and the inserted objects are displayed to assist a physician in executing a procedure. The CARTO™ System is an example of a system that includes location sensing technologies for determining position of an object within the body, mapping technology to build maps of anatomy (e.g. heart), and a workstation to display the graphical representations of anatomy and the inserted objects. <CIT> relates to methods of assessing contact between an electrode and tissue using complex impedance measurements.

Systems and methods presented herein generally include determining that electrodes of an end effector are in contact with tissue and displaying the tissue contact graphically. Locations of electrodes of the end effector can be determined using advanced current location. Magnitude of contact between electrodes and tissue can be determined based on impedance measurements between the electrodes in contact with tissue and one or more reference electrodes (e.g. body patch(es)). Three electrodes in contact with tissue can define a plane and a vector that can be graphically displayed to indicate tissue location and orientation with respect to the end effector.

The current invention is defined by the appended claims.

An example location-measuring system can include a medical probe, at least three electrode pads, a display, a memory, and a processor. The medical probe can include a plurality of electrodes. The at least three electrode pads can be configured to define a circuit between the each of the plurality of electrodes for measurement of impedance from each circuit. The processor can be operatively coupled to the memory, medical probe, and display. The processor can be configured to receive one or more impedance values from the plurality of electrodes in contact with a tissue of an organ, locate each of the plurality of electrodes within the organ based on triangulation by impedance measurements, select at least three electrodes having impedance values indicative of sufficient tissue contact with the organ, define a plane between the at least three electrodes, determine a centroid of the plane based at least in part on the locations of the at least three electrodes in the organ, and display a visual representation of the at least three electrodes connected by the plane and the centroid of the plane with respect to an anatomical representation of the organ.

The processor can further be configured to display an arrow extending from the centroid with respect to the anatomical representation of the organ.

Vertices of the plane can be defined by a central point on the plurality of electrodes.

The processor can further be configured to determine a center of mass for the at least three electrodes based on the respective impedance values of the at least three electrodes. The center of mass can be represented by a line orthogonal to the plane. The processor can further be configured to display a contact vector intersecting the orthogonal line.

The processor can further be configured to determine a spatial relationship between the plurality of electrodes and the at least three electrode pads based on a difference in impedance values from the at least three electrodes in contact with the tissue of the organ. The processor can further be configured to estimate, by the plane and the spatial relationship, a contact vector indicative of a magnitude of force and a direction of force of the medical probe against the tissue of the organ.

The one or more impedance values can be indicative of a magnitude of force of a respective electrode in contact with the tissue of the organ.

The contact vector can be aligned approximately central within the plane.

The spatial relationship between the plurality of electrodes and the at least three electrode pads can be indicative of an applied force between the at least three electrodes and the tissue of the organ.

The medical probe can further include an expandable basket assembly having a plurality of spines configured to bow radially outward from a collapsed configuration to an expanded configuration. The basket assembly can be configured to deform when at least a portion of the medical probe is in contact with the tissue.

The processor can be configured to adapt a contact vector based on a change in spatial relationship when the basket assembly undergoes deformation during contact with the tissue.

The processor can further be configured to display a visual representation of a contact vector in relation to the tissue of the organ.

The processor can further be configured to locate the medical probe based on a magnetic sensor disposed proximate the probe and based on a plurality of reference electromagnetic (EM) sensors. The reference EM sensors can define an EM coordinate system and a body coordinate system.

An example method for providing visual indicators of electrode contact to tissue of an organ by a catheter end effector having a plurality of electrodes can include the following steps, performed in a variety of orders, and with interleaving steps. The method can include determining location of at least a portion of the plurality of electrodes based at least in part on impedance measurements between a respective electrode and ground pads, selecting at least three electrodes of the plurality of electrodes that are in contact with the tissue, defining a plane contiguous to the at least three electrodes in contact with the tissue, and displaying a visual indicator of the plane with respect to a visual representation of the organ.

The method can further include identifying the at least three electrodes in contact with the tissue based at least in part on the impedance measurements between the respective electrode and ground pads.

The method can further include determining a centroid of the plane based on locations of the at least three electrodes in contact with the tissue.

The method can further include determining a center of mass for the at least three electrodes in contact with tissue, the center of mass being based on the respective impedance values of the at least three electrodes. The method can further include displaying a line orthogonal to the plane, the line representing the center of mass. The method can further include displaying a contact vector intersecting the orthogonal line. The contact vector can be aligned approximately central within the plane.

The method can further include orienting the medical probe based on a magnetic sensor disposed proximate the electrodes and a plurality of external reference electromagnetic (EM) sensors, the reference EM sensors defining an EM coordinate system and a body coordinate system.

The medical probe can include an expandable basket assembly having a plurality of spines extending along a longitudinal axis and converging at a central spine intersection. Each spine of the plurality of spines can having at least two electrodes thereon.

The method can further include configuring a point of each electrode as a vertex for the plane formed between the respective electrodes in contact with the tissue.

The method can further include aligning the contact vector approximately orthogonal to the plane.

The method can further include aligning the contact vector approximately central in the plane.

The method can further include adapting the contact vector based on a change in spatial relationship when the medical probe undergoes deformation during contact with the tissue of the organ.

The method can further include delivering, via the electrodes in contact with the tissue, electrical pulses for irreversible electroporation, the electrical pulses having a peak voltage of at least <NUM> volts (V).

The method can further include delivering, via spray ports, an irrigation fluid to the electrodes.

An example method for displaying visual representation of electrodes of a catheter in relation to an organ can include the following steps performed in a variety of orders and including interleaving steps. The method can include receiving one or more impedance values from a plurality of electrodes at a distal end of the catheter and in contact with a tissue of the organ. The method can include locating each of the plurality of electrodes within the organ based on triangulation by impedance measurements. The method can include selecting at least three electrodes having impedance values indicative of sufficient tissue contact with the organ. The method can include defining a plane between the at least three electrodes. The method can include determining a centroid of the plane based at least in part on the locations of the at least three electrodes in the organ. The method can include displaying on a screen a visual representation of the at least three electrodes connected by the plane and the centroid of the plane with respect to an anatomical representation of the organ.

The above and further aspects of this invention are further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation.

As used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. In addition, vasculature of a "patient," "host," "user," and "subject" can be vasculature of a human or any animal. It should be appreciated that an animal can be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal can be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject can be any applicable human patient, for example.

As used herein, the term "proximal" indicates a location closer to the operator or physician whereas "distal" indicates a location further away to the operator or physician.

As used herein, "operator" can include a doctor, surgeon, technician, scientist, or any other individual or delivery instrumentation associated with delivery of a multi-electrode catheter for the treatment of drug refractory atrial fibrillation to a subject.

As used herein, the term "ablate" or "ablation", as it relates to the devices and corresponding systems of this disclosure, refers to components and structural features configured to reduce or prevent the generation of erratic cardiac signals in the cells by utilizing non-thermal energy, such as irreversible electroporation (IRE), referred throughout this disclosure interchangeably as pulsed electric field (PEF) and pulsed field ablation (PFA). Ablating or ablation as it relates to the devices and corresponding systems of this disclosure is used throughout this disclosure in reference to non-thermal ablation of cardiac tissue for certain conditions including, but not limited to, arrhythmias, atrial flutter ablation, pulmonary vein isolation, supraventricular tachycardia ablation, and ventricular tachycardia ablation. The term "ablate" or "ablation" also includes known methods, devices, and systems to achieve various forms of bodily tissue ablation, including thermal ablation, as understood by a person skilled in the relevant art.

As discussed herein, the terms "bipolar", "unipolar", and "monopolar" when used to refer to ablation schemes describe ablation schemes which differ with respect to electrical current path and electric field distribution. "Bipolar" refers to ablation scheme utilizing a current path between two electrodes that are both positioned at a treatment site; current density and electric flux density is typically approximately equal at each of the two electrodes. "Unipolar" and "monopolar" are used interchangeably herein to refer to ablation scheme utilizing a current path between two electrodes where one electrode including a high current density and high electric flux density is positioned at a treatment site, and a second electrode including comparatively lower current density and lower electric flux density is positioned remotely from the treatment site.

As discussed herein, the terms "tubular" and "tube" are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structures are generally illustrated as a substantially right cylindrical structure. However, the tubular structures may have a tapered or curved outer surface without departing from the scope of the present disclosure.

The term "temperature rating", as used herein, is defined as the maximum continuous temperature that a component can withstand during its lifetime without causing thermal damage, such as melting or thermal degradation (e.g., charring and crumbling) of the component.

Any one or more of the teachings, expressions, versions, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, versions, examples, etc. that are described herein. The following-described teachings, expressions, versions, examples, etc. should therefore not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined will be readily apparent to those skilled in the pertinent art in view of the teachings herein.

<FIG> is an illustration showing an example catheter-based electrophysiology mapping and ablation system <NUM>. The system <NUM> includes multiple catheters, which are percutaneously inserted by a physician <NUM> through the patient's vascular system into a chamber or vascular structure of a heart <NUM>. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location in the heart <NUM>. Thereafter, a plurality of catheters can be inserted into the delivery sheath catheter so as to arrive at the desired location. The plurality of catheters may include catheters dedicated for sensing Intracardiac Electrogram (IEGM) signals, catheters dedicated for ablating and/or catheters dedicated for both sensing and ablating. An example catheter <NUM> that is configured for sensing IEGM and ablation is illustrated herein. The physician <NUM> brings a distal tip <NUM> of the catheter <NUM> into contact with the heart wall for sensing a target site in the heart <NUM>.

The illustrated catheter <NUM> is an exemplary catheter that includes one and preferably multiple electrodes <NUM> optionally distributed over a plurality of spines <NUM> of a basket assembly <NUM> at distal tip <NUM> and configured to sense the IEGM signals and provide ablation signals. Catheter <NUM> may additionally include a position sensor <NUM> embedded in or near distal tip <NUM> for tracking position and orientation of distal tip <NUM>. Optionally and preferably, position sensor <NUM> is a magnetic based position sensor including three magnetic coils for sensing three-dimensional (3D) position and orientation.

A magnetic based position sensor <NUM> may be operated together with a location pad <NUM> including a plurality of magnetic coils <NUM> configured to generate magnetic fields in a predefined working volume. Real time position of a distal tip <NUM> of the catheter <NUM> may be tracked based on magnetic fields generated with a location pad <NUM> and sensed by a magnetic based position sensor <NUM>. Details of the magnetic based position sensing technology are described in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

The system <NUM> includes one or more electrode patches <NUM> positioned for skin contact on the patient <NUM> to establish location reference for location pad <NUM> as well as impedance-based tracking of electrodes <NUM>. For impedance-based tracking, electrical current is directed toward electrodes <NUM> and sensed at electrode skin patches <NUM> so that the location of each electrode can be triangulated via the electrode patches <NUM>. Details of the impedance-based location tracking technology are described in <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

The magnetic based position sensor <NUM> can be used to calibrate impedance-based tracking of the electrodes <NUM>. The workstation <NUM> can be configured to locate the distal tip <NUM> of the catheter <NUM> based on the magnetic sensor <NUM> and a plurality of reference electromagnetic (EM) sensors. The reference EM sensors can be configured to define an EM coordinate system and a body coordinate system.

A recorder <NUM> displays electrograms <NUM> captured with body surface ECG electrodes <NUM> and intracardiac electrograms (IEGM) captured with electrodes <NUM> of the catheter <NUM>. The recorder <NUM> may include pacing capability for pacing the heart rhythm and/or may be electrically connected to a standalone pacer.

The system <NUM> can include an ablation energy generator <NUM> that is adapted to conduct ablative energy to one or more of electrodes at a distal tip of a catheter configured for ablating. Energy produced by the ablation energy generator <NUM> may include, but is not limited to, radiofrequency (RF) energy or pulsed-field ablation (PFA) energy, including monopolar or bipolar high-voltage DC pulses as may be used to effect irreversible electroporation (IRE), or combinations thereof.

A patient interface unit (PIU) <NUM> is an interface configured to establish electrical communication between catheters, electrophysiological equipment, power supply and a workstation <NUM> for controlling operation of system <NUM>. Electrophysiological equipment of the system <NUM> may include for example, multiple catheters, a location pad <NUM>, body surface ECG electrodes <NUM>, electrode patches <NUM>, an ablation energy generator <NUM>, and a recorder <NUM>. Optionally and preferably, the PIU <NUM> includes processing capability for implementing real-time computations of location of the catheters and for performing ECG calculations.

The workstation <NUM> includes memory, processor unit with memory or storage with appropriate operating software loaded therein, and user interface capability. The workstation <NUM> can be configured to provide multiple functions, optionally including (<NUM>) modeling the endocardial anatomy in three-dimensions (3D) and rendering the model or an anatomical map <NUM> for display on a display device <NUM>; (<NUM>) displaying on the display device <NUM> activation sequences (or other data) compiled from recorded electrograms <NUM> in representative visual indicia or imagery superimposed on the rendered anatomical map <NUM>; (<NUM>) displaying real-time location and orientation of multiple catheters within the heart chamber; and (<NUM>) displaying on the display device <NUM> sites of interest such as places where ablation energy has been applied. One commercial product embodying elements of the system <NUM> is available as the CARTO™ <NUM> System, available from Biosense Webster, Inc. , 31A Technology Drive, Irvine, CA <NUM>.

The workstation <NUM> can further be adapted to detection tissue contact using impedance measurements. Details of impedance-based tissue contact, based on the impedance between the catheter electrode <NUM> and a return electrode <NUM>, are described in <CIT>; <CIT>; <CIT>; and <CIT>.

The workstation <NUM> can further be adapted to detect tissue contact by an electrode <NUM> by monitoring electrical currents between electrode patches <NUM> and the electrode <NUM>. Details of current-based tissue contact detection are described in <CIT>.

When the distal end <NUM> of the catheter <NUM> moves, the relative impedance with respect to at least one patch <NUM> changes. The measurement of the change in relative impedance thereby permits tracking of the distal end <NUM>. By contrast, when catheter electrode <NUM> touches internal tissue, the currents at the patches <NUM> will change, but the values of relative impedance will not change. Consequently, as noted above, errors in position measurement due to tissue contact are reduced when the methods described above are used. These methods further provide a means of evaluating internal tissue contact by sensing when changes in current are not reflected by changes in the relative impedances.

The workstation <NUM> can further be adapted to detect that at least three of the electrodes <NUM> of the distal tip <NUM> of the catheter <NUM> that are in contact with tissue, and display, on the display <NUM>, a visual representation of the at least three electrodes connected by a plane with respect to an anatomical representation of the heart <NUM>. The workstation can further display a centroid of the plane with respect to the anatomical representation of the heart <NUM>. In order to determine which electrodes <NUM> are in contact with tissue, the workstation <NUM> can be configured to receive one or more impedance values from the electrode <NUM> that are in contact with tissue of the heart <NUM>, and select at least three electrodes <NUM> having impedance values indicative of sufficient tissue contact with the heart <NUM>. In order to determine the spatial relationship of the electrodes <NUM> within the heart <NUM>, the workstations can be configured to locate at least a portion of the electrodes <NUM> based on triangulation by impedance measurements. The workstation <NUM> can be configured to define the plane between the at least three electrodes <NUM> and the centroid of the plane based at least in part on the locations of the at least three electrodes that are in contact with tissue in the heart <NUM>.

The system <NUM> can further include an irrigation source (not illustrated) configured to provide irrigation fluid to the catheter <NUM>. The workstation <NUM> can be configured to control the irrigation source to provide irrigation at the distal end <NUM> of the catheter <NUM>.

<FIG> is a schematic pictorial illustration showing a perspective view of a medical probe <NUM> including a basket assembly <NUM> in an expanded form when unconstrained, such as by being advanced out of an insertion tube lumen <NUM> (<FIG>) at a distal end <NUM> of an insertion tube <NUM>. The medical probe <NUM> illustrated in <FIG> can be configured similarly to the catheter <NUM> illustrated in <FIG>.

<FIG> shows the basket assembly <NUM> in a collapsed form within insertion tube <NUM> of a guide sheath. In the expanded form (<FIG>), spines <NUM> bow radially outwardly, and in the collapsed form (<FIG>) the spines are arranged generally along a longitudinal axis <NUM> of insertion tube <NUM>.

As shown in <FIG>, basket assembly <NUM> includes a plurality of flexible spines <NUM> that are formed at the end of a tubular shaft <NUM>. During a medical procedure, medical professional <NUM> (<FIG>) can deploy the basket assembly <NUM> by extending tubular shaft <NUM> from the insertion tube <NUM>, causing the basket assembly <NUM> to exit the insertion tube <NUM> and transition to the expanded form. Spines <NUM> may have elliptical (e.g., circular) or rectangular (that may appear to be flat) cross-sections, and include a flexible, resilient material (e.g., a shape-memory alloy such as nickel-titanium, also known as Nitinol) forming a strut.

The plurality of flexible spines <NUM> converge at a central spine intersection at a distal end <NUM> of the basket assembly <NUM>. In some examples, the central spine intersection <NUM> can include one or more cutouts that allow for bending of the spines <NUM> when each spine respective attachment end is connected to the spine retention hub <NUM>.

In embodiments described herein, one or more electrodes <NUM> positioned on spines <NUM> of basket assembly <NUM> can be configured to deliver ablation energy (RF and/or IRE) to tissue in heart <NUM>. Additionally, or alternatively, the electrodes <NUM> can also be used to determine the location of basket assembly <NUM> and/or to measure a physiological property such as local surface electrical potentials at respective locations on tissue in heart <NUM>. The electrodes <NUM> can be biased such that a greater portion of the one or more electrodes <NUM> face outwardly from basket assembly <NUM> such that the one or more electrodes <NUM> deliver a greater amount of electrical energy outwardly away from the basket assembly <NUM> (i.e., toward the heart <NUM> tissue) than inwardly.

Examples of materials ideally suited for forming electrodes <NUM> include gold, platinum and palladium (and their respective alloys). These materials also have high thermal conductivity which allows the minimal heat generated on the tissue (i.e., by the ablation energy delivered to the tissue) to be conducted through the electrodes to the back side of the electrodes (i.e., the portions of the electrodes on the inner sides of the spines), and then to the blood pool in heart <NUM>.

The medical probe <NUM> can include a spine retention hub <NUM> that extends longitudinally from a distal end of tubular shaft <NUM> towards distal end <NUM> of basket assembly <NUM>. The system <NUM> can include an irrigation module that delivers irrigation fluid to basket assembly <NUM> through the tubular shaft <NUM>.

<FIG> illustrates triangular planes <NUM> that each include three electrodes <NUM>. For instance, a distal plane 41a at the distal end <NUM> of the basket assembly <NUM> is defined by three electrodes 40a, 40b, 40c nearest the distal end <NUM>. Additional planes <NUM> are defined by electrode trios 40b, 40c, 40d; 40c, 40d, 40e; 40b, 40d, <NUM>; 40d, 40e, 40f; and 40d, 40f, <NUM> as illustrated.

<FIG> illustrates features of each plane <NUM>, using the distal plane 41a as an example. The plane 41a has three vertices A, B, C each defined by a central point of a respective electrode 40a, 40b, 40c. Each plane <NUM> has edges AB, BC, AC between the vertices A, B, C. <FIG> also illustrates a vector <NUM> positioned centrally within the plane 41a and pointing orthogonally from the plane 41a away from the basket assembly <NUM>. The vector <NUM> can provide a visual indication of tissue location and orientation.

<FIG> is an illustration of a graphical representation of a left atrium LA of a heart, a medical probe <NUM>, and a plane <NUM> and a vector <NUM> indicating tissue location and orientation of contacted tissue. The graphical representation can be displayed on display <NUM> of workstation <NUM> to provide a visual aid to the physician <NUM>. Electrodes in contact with tissue can be used to create the vector <NUM> and the plane <NUM>. Additionally, dynamic visualization of frame geometry (deformation) may be achieved by determining electrode positions relative to the electrode patches <NUM> (<FIG>) using impedance-based location sensing, which can allow for the vector <NUM> to adapt to changes in frame geometry (e.g. frame deformation during contact with tissue).

<FIG> is an illustration of a first example plane <NUM> and vector 42a determined by impedance. The locations of the three vertices A, B, C of the plane <NUM> can be determined by position sensing, for instance via impedance-based tracking, such as described in <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

Additionally, or alternatively, the locations of the three vertices A, B, C of the plane <NUM> can be determined by magnetic based position sensing technology, such as described in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>;<CIT>; <CIT>; <CIT>; <CIT>; <CIT>.

The contact impedance of each electrode at each of the three vertices A, B, C can be detected by methods as described in <CIT>, <CIT>, <CIT>, and <CIT>.

In the illustrated example, vertex A has an impedance of <NUM> ohms, vertex B has an impedance of <NUM> ohms, and vertex C has an impedance of <NUM> ohms. The specific numerical values of impedance are selected purely for the sake of illustration and may have an alternative value consistent with the configuration of the system <NUM> as understood by a person skilled in the pertinent art. For the sake of the example, consider that sufficient contact is determined when the tissue contact measures at least <NUM> ohms. In the example, larger impedance is indicative of contact of a larger portion of surface area of the electrode <NUM> to tissue.

Additionally, or alternatively to the contact impedance at each vertex electrode <NUM>, a current-based tissue contact method detection can be used, such as described in <CIT>.

When catheter <NUM> moves, the relative impedance with respect to at least one patch <NUM> changes. The measurement of the change in relative impedance thereby permits tracking of the catheter <NUM>. By contrast, when catheter electrode <NUM> touches internal tissue, the currents at the patches <NUM> will change, but the values of relative impedance may not change. Consequently, errors in position measurement due to tissue contact are reduced when the methods described in <CIT> are used. These methods further provide a means of evaluating internal tissue contact by sensing when changes in current are not reflected by changes in the relative impedances. Currents at the patches <NUM> can therefore be used as another metric for determining tissue contact.

The vector 42a illustrated in <FIG> extends from a centroid <NUM> of the plane <NUM>. The centroid <NUM> is the center point of the plane <NUM>. Because the plane <NUM> is triangular, the geometrical definition of the centroid <NUM> of the plane <NUM> is the point in which the three medians of the triangle intersect. The median is a line that joins the midpoint of a side and the opposite vertex of the triangle. The centroid of the triangle separates the median in the ratio of <NUM>:<NUM>. The x,y coordinates of the centroid <NUM> can be found by taking the average of x-coordinate points and y-coordinate points of all the vertices A, B, C of the triangle. The vector 42a can extend orthogonal to the plane <NUM>, pointing toward tissue. In this example, the impedance at each vertex A, B, C is used to select the electrodes that are in contact with the tissue (e.g. electrodes having highest impedance) to define the plane <NUM>. The vector 42a can be useful to the physician <NUM> to be able to visualize the central point contacted by the electrodes <NUM> and the direction of the tissue in relation to the electrodes <NUM>.

<FIG> is an illustration of the plane <NUM> and a second example vector 42b determined by impedance. The plane <NUM> and the vertices A, B, C can be determined as disclosed in relation to <FIG> and elsewhere herein. A center of mass <NUM> of the plane can be determined based on the locations of each vertex and the relative impedance at each vertex through well-known center of mass calculations. Given that the plane is a triangle, consider that each vertex A, B, C has a respective (x,y)-coordinate (xA, yA), (xB, yB), (xC, yC) and the impedance represents a respective mass mA, mB, mC, then the x-coordinate xCM of the center of mass <NUM> can be calculated by the formula xCM = (xAmA + xBmB + xCmC) / M, and the y-coordinate yCM of the center of mass <NUM> can be calculated by the formula yCM = (yAmA + yBmB + yCmC) / M, where M = mA + mB + mC. The vector 42b can extend orthogonal to the plane <NUM>, pointing toward tissue. The vector 42b can be useful to the physician <NUM> to be able to visualize a difference in contact area between the three electrodes <NUM> at the vertices A, B, C. The closer the center of mass <NUM> is to the centroid <NUM>, the more balanced the impedance is at the vertices A, B, C, and therefore the more balanced the contact area is between the electrodes <NUM> at the vertices A, B, C. A physician <NUM> may choose to adjust the position of the basket assembly <NUM> to provide a desired distribution of contact between the electrodes <NUM>. The direction of the vector 42b indicates position of tissue.

<FIG> is an illustration of the plane <NUM> and a third example vector 42c determined by impedance. The plane <NUM> and the vertices A, B, C can be determined as disclosed in relation to <FIG> and elsewhere herein. The centroid <NUM> can be determined as disclosed in relation to <FIG>. The center of mass <NUM> can be determined as disclosed in relation to <FIG>. The vector 42b from the center of mass <NUM> can be determined as disclosed in relation to <FIG>. In <FIG>, the center of mass vector 42b represents a line orthogonal to plane <NUM> that passes through the center of mass <NUM>. A contact vector 42c extends from the centroid and intersects the orthogonal line of vector 42b rather than extending orthogonal to the plane <NUM>. The vector 42c can be useful to the physician <NUM> to be able to visualize a difference in contact area between the three electrodes <NUM> at the vertices A, B, C. The closer the center of mass <NUM> is to the centroid <NUM>, the more orthogonal the vector 42c through the centroid <NUM> becomes to the plane <NUM>. The closer the center of mass <NUM> is to the centroid <NUM>, the more balanced the impedance is at the vertices A, B, C, and therefore the more balanced the contact area is between the electrodes <NUM> at the vertices A, B, C. A physician <NUM> may choose to adjust the position of the basket assembly <NUM> to provide a desired distribution of contact between the electrodes <NUM>.

In summary, a first vector 42a illustrated in <FIG> extends from the centroid <NUM> orthogonal to the plane <NUM>; a second vector 42b illustrated in <FIG> extends from the center of mass <NUM> orthogonal to the plane <NUM>; and a third vector 42c illustrated in <FIG> extends from the centroid and intersects the orthogonal line of vector 42b. The plane <NUM> is approximately parallel to the tissue and near to the tissue to indicate location of the tissue in contact with the basket assembly <NUM>. The vector(s) 42a, 42b, 42c therefore displayed in relation to the tissue at least by virtue of being displayed in relation to the plane <NUM>. A graphical representation of the tissue may also be displayed.

The workstation <NUM> illustrated in <FIG> can be configured to display the first vector 42a, the second vector 42b, the third vector 42c, or any sub-combination thereof. The workstation <NUM> can be configured to allow the physician <NUM> to select which vector(s) 42a, 42b, 42c to display.

Impedance can be indicative of surface area contact of the electrodes <NUM> at the vertices A, B, C to tissue. A greater force applied to the electrode into tissue generally results in greater surface area contact. The workstation <NUM> can therefore be configured to estimate, based at least in part on geometry of the plane <NUM> and impedance at the vertices A, B, C a magnitude of force and a direction of force of the medical probe against the tissue of the organ. The length of a vector 42a, 42b, 42c displayed can be based at least in part on the magnitude of the force. The direction of the third vector 42c (<FIG>) can be based at least in part on the direction of the force.

The magnitude and/or direction of the force may additionally, or alternatively be estimated based on position of the electrodes <NUM> including electrodes <NUM> not in contact with tissue. For instance, the basket assembly <NUM> can have a predetermined shape that the basket assembly <NUM> takes when unconstrained and in free space (e.g. suspended in blood, air, or other fluid), and the basket assembly <NUM> can be deformed from the predetermined shape when pressed to tissue. The spatial relationship between the electrodes <NUM> in the predetermined shape can be determined when the basket assembly <NUM> is not in contact with tissue, for example through impedance-based location sensing, and/or magnetic-based location sensing, or other location techniques as understood by a person skilled in the pertinent art. Spatial relationship between electrodes <NUM> can again be determined when the basket assembly <NUM> is in contact with tissue. The mechanical properties of the basket <NUM> can be known such that the force and direction of force on the basket <NUM> due to tissue contact can be calculated based on the deformed shape of the basket <NUM>. For instance, spring constant of the spines <NUM> can be known, and the force can be calculated based at least in part on the spring constant. Additionally, or alternatively, the probe <NUM> can be calibrated using a testing apparatus prior to treatment such that various forces are applied to the basket <NUM> and the deformed shape of the basket <NUM> is observed, and calibration information is stored in memory of the catheter <NUM> and/or workstation <NUM> so that the force can be calculated based on the calibration information and observed deformation of the basket assembly <NUM>. The length of a vector 42a, 42b, 42c displayed can be based at least in part on the magnitude of the force. The direction of the third vector 42c (<FIG>) can be based at least in part on the direction of the force. The workstation <NUM> can be configured to dynamically adapt the displayed contact vector(s) 42a, 42b, 42c when the basket assembly <NUM> undergoes deformation during contact with tissue.

The foregoing methods for calculating the magnitude and/or direction of the force may eliminate the need for a contact force sensor in some applications. However, the medical probe <NUM> may include a contact force sensor (not illustrated) disposed inside tube <NUM> (<FIG>) and proximally in relation to basket assembly <NUM> and as close as possible to the basket assembly <NUM> so that contact with cardiac tissue by electrodes <NUM> can be transmitted to the contact force sensor. The contact force sensor can be used in addition to, or as an alternative to utilizing impedance at the electrodes in contact with tissue to determine contact force and therefore visual display of the contact vector(s) 42a, 42b, 42c. The contact force sensor can be used in addition to, or as an alternative to utilizing deformation of the basket <NUM> to determine contact force and therefore visual display of the contact vector(s) 42a, 42b, 42c. Details of an example contact force sensor are provided in <CIT>, which disclosure is incorporated by reference herein and attached to the Appendix of priority patent Application No. <CIT>.

While the examples illustrated herein include a basket assembly <NUM>, the principles of the systems and methods disclosed herein can be applied to various catheter geometries including other spherical catheters (e.g. balloon), planar catheters, ray catheters (e.g. PENTARAY®), alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. While the example planes <NUM> illustrated herein are defined by three electrodes in contact with tissue, a catheter geometry having more than three electrodes in a plane can result in a displayed plane defined by more than three electrodes. A centroid and a center of mass of such a plane can be calculated based on more than three vertices as understood by a person skilled in the pertinent art. Likewise, the force magnitude and direction of a catheter end effector against tissue, and therefore the vector displayed, can be determined for alternative catheter geometries as understood by a person skilled in the pertinent art. Further electrodes <NUM> can have a variety of cross-sectional shapes, curvatures, lengths, etc. The illustrated electrode <NUM> is offered to illustrate one various configuration of electrodes <NUM> that can be used with the medical device <NUM> but should not be construed as limiting. One skilled in the art will appreciate that various other configurations of electrodes <NUM> can be used with the disclosed technology without departing from the scope of this disclosure. The distal end <NUM> of the catheter <NUM> can carry alternative numbers of electrodes in alternative spacings as understood by a person skilled in the pertinent art.

<FIG> is a flow diagram of a method <NUM> for providing visual indicators of electrode contact to tissue of an organ by a catheter end effector having a plurality of electrodes. The catheter can be configured similarly to the catheter <NUM> and/or medical probe <NUM> illustrated herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. The organ can include a heart or other organ that can be accessed by catheter-based system.

At step <NUM>, a location of at least a portion of the plurality of electrodes is determined. The location can be determined based at least in part on impedance measurements between a respective electrode and ground pads. The impedance measurements can be made using methods disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. The location can be determined for electrodes in contact with tissue. Location can additionally be determined for electrodes not in contact with tissue.

At step <NUM>, at least three electrodes that are in contact with tissue can be selected from the plurality of electrodes. The electrodes can be determined to be in contact with tissue based on methods disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. For instance, at least three electrodes in contact with tissue can be identified based at least in part on impedance measurements between the respective electrode and ground pads.

At step <NUM>, a plane contiguous to the electrodes in contact with tissue, selected at step <NUM>, can be defined. The plane can be configured similarly to the plane <NUM> illustrated herein, planes otherwise disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art.

At step <NUM>, a visual indicator of the plane can be displayed with respect to a visual representation of the organ. For instance, see <FIG>. The plane and the organ may be otherwise displayed by modifying graphical representations of the CARTO™ system, nGEN, alternatives thereto, and variations thereof to include a plane displayed with respect to the organ as understood by a person skilled in the pertinent art. Each electrode in contact with tissue can be configured as a vertex for the plane.

The method <NUM> can further include additional steps. A centroid of the plane can be determined based on locations of the electrodes in contact with tissue. A center of mass can be determined for the electrodes in contact with tissue. The center of mass can be based on the respective impedance values of the electrodes. A line orthogonal to the plane at the center of mass can be displayed. A contact vector intersecting the orthogonal line can be displayed, and may not be orthogonal to the plane. More than one contact vector can be displayed, and the vector(s) can extend from the centroid and/or the center of mass. A vector may be orthogonal to the plane. The vector can be adapted based on a change in spatial relationship when the medical probe undergoes deformation during contact with tissue of the organ. Electrical pulses can be delivered to the electrodes in contact with tissue for irreversible electroporation. The electrical pulses can have a peak voltage of at least <NUM> V. Irrigation fluid can be delivered via spray ports to the electrodes.

<FIG> is a flow diagram of a method <NUM> for displaying visual representation of electrodes of a catheter in relation to an organ. The catheter can be configured similarly to the catheter <NUM> and/or medical probe <NUM> illustrated herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. The organ can include a heart or other organ that can be accessed by catheter-based system.

At step <NUM>, one or more impedance values can be received from a plurality of electrodes at a distal end of the catheter and in contact with tissue of the organ. The impedance values can be determined based at least in part on impedance measurements between a respective electrode and ground pads. The impedance measurements can be made using methods disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. The location can be determined for electrodes in contact with tissue.

At step <NUM>, each of the plurality of electrodes can be located within the organ based on triangulation impedance measurements. The triangulation impedance measurements can be determined based at least in part on impedance measurements between a respective electrode and ground pads. The triangulation impedance measurements can be made using methods disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art. The location can be determined for electrodes in contact with tissue. Location can additionally be determined for electrodes not in contact with tissue.

At step <NUM>, at least three electrodes that have impedance values indicative of sufficient tissue contact with the organ can be selected. The electrodes can be selected based on the impedance values being over a predetermined threshold and/or by comparing impedance values of electrodes of the catheter to each other and selecting electrodes having impedances most indicative of contact (e.g. highest impedances). The electrodes can otherwise be selected as disclosed herein, alternatives thereto, and variations thereof as understood by a person skilled in the pertinent art.

At step <NUM>, a plane can be defined between the electrodes selected at step <NUM>. The plane can have a vertex for at least three of the electrodes selected at step <NUM>.

At step <NUM>, a centroid of the plane can be determined based at least in part on the locations of the at least three electrodes in the organ.

At step <NUM>, a visual representation of the three electrodes selected at step <NUM> connected by the plane defined at step <NUM> can be displayed on a screen with respect to an anatomical representation of the organ. The centroid of the plane determined at step <NUM> can be displayed.

Having shown and described exemplary embodiments of the subject matter contained herein, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications without departing from the scope of the claims. In addition, where methods and steps described above indicate certain events occurring in certain order, it is intended that certain steps do not have to be performed in the order described but in any order as long as the steps allow the embodiments to function for their intended purposes.

Claim 1:
A location-measuring system (<NUM>), comprising:
a medical probe comprising a plurality of electrodes; electrodes (<NUM>);
at least three electrode pads (<NUM>) configured to define a circuit between the each of the plurality of electrodes for measurement of impedance from each circuit;
a display; display (<NUM>);
a memory; and
a processor operatively coupled to the memory, medical probe and display, the processor configured to:
receive one or more impedance values from the plurality of electrodes in contact with a tissue of an organ;
locate each of the plurality of electrodes within the organ based on triangulation by impedance measurements;
select at least three electrodes of the plurality of electrodes such that the at least three electrodes have impedance values indicative of sufficient tissue contact with the organ;
define a plane between the at least three electrodes;
determine a centroid (<NUM>) of the plane based at least in part on the locations of the at least three electrodes in the organ; and
display, on the display, a visual representation of the at least three electrodes connected by the plane and the centroid of the plane with respect to an anatomical representation of the organ.