Patent Description:
<CIT> discloses multi-arm probe rendering. In one embodiment, a medical procedure system, a probe including a shaft, deflectable arms, a position sensor on the shaft, and electrodes along each arm, and processing circuitry to measure readings of the sensor, compute first position coordinates of proximal ends of the arms responsively to the readings and a predefined spatial relation between the sensor and proximal ends, measure an indication of electrical impedances between body surface electrodes and at least two electrodes of each arm, compute second position coordinates of each of the at least two electrodes on each arm responsively to the indication, fit a respective curve corresponding to each arm responsively to the respective first position coordinates of the respective proximal end and the second position coordinates of each of the respective at least two electrodes, and render a graphical representation of the probe including the deflectable arms responsively to the respective fitted curve.

The invention is defined in claims <NUM>, <NUM> and <NUM>. Embodiments are provided in the dependent claims.

A technique is described herein. The technique includes processing endpoint location data and spline tangent data for a catheter to calculate Bezier curve control points; and based on the Bezier curve control points, determining estimated electrode positions for the catheter.

<FIG> is a diagram of an example system (e.g., medical device equipment), shown as a system <NUM>, in which one or more features of the subject matter herein can be implemented according to one or more embodiments. All or part of the system <NUM> can be used to detect, diagnose, and/or treat cardiac conditions.

The system <NUM>, as illustrated, includes a catheter <NUM>, which includes a manipulator <NUM>, a shaft <NUM> disposed through a sheath <NUM>, and a distal tip in the shape of a basket (referred to herein as a "catheter basket" <NUM>). The catheter basket <NUM> includes a plurality of electrodes <NUM> disposed on a plurality of bendable splines <NUM>. A puller element <NUM> pulls or pushes the distal end <NUM> of the catheter basket <NUM>, expanding or collapsing the catheter basket <NUM>. In some examples, the catheter basket <NUM> includes one or more position sensors that allow sensing of the position of the proximal end and distal end of the catheter basket <NUM>. Also illustrated in <FIG> are a physician <NUM> (or a medical professional, technician, clinician, etc.), a heart <NUM>, a patient <NUM>, and a bed <NUM> (or a table). Note that insets <NUM> and <NUM> show the heart <NUM> and the catheter <NUM> in greater detail. The system <NUM> also, as illustrated, includes a console <NUM> (including one or more processors <NUM> and memories <NUM> providing controlling and processing capability) and a display <NUM>. Note further each element and/or item of the system <NUM> is representative of one or more of that element and/or that item. The example of the system <NUM> shown in <FIG> can be modified to implement the embodiments disclosed herein. The disclosed embodiments can similarly be applied using other system components and settings. Additionally, the system <NUM> can include additional components, such as elements for sensing electrical activity, wired or wireless connectors, processing and display devices, or the like.

The system <NUM> can be utilized to detect, diagnose, and/or treat cardiac conditions. Cardiac conditions, such as cardiac arrhythmias, persist as common and dangerous medical ailments, especially in the aging population. For instance, the system <NUM> can be part of a surgical system (e.g., CARTO® system sold by Biosense Webster) that is configured to obtain biometric data (e.g., anatomical and electrical measurements of a patient's organ, such as the heart <NUM>) and perform a cardiac ablation procedure. According to one or more embodiments, the biometric data can include anatomical and electrical measurements acquired in a significant portion of an atrium during the mapping and ablation procedures.

More particularly, treatments for cardiac conditions such as cardiac arrhythmia often require obtaining a detailed mapping of cardiac tissue, chambers, veins, arteries and/or electrical pathways. For example, a prerequisite for performing a catheter ablation (as described herein) successfully is that the cause of the cardiac arrhythmia is accurately located in a chamber of the heart <NUM>. Such locating may be done via an electrophysiological investigation during which electrical potentials are detected and spatially resolved with a mapping catheter (e.g., the catheter <NUM>) introduced into the chamber of the heart <NUM>. This electrophysiological investigation, the so-called electro-anatomical mapping, thus provides 3D mapping data which can be displayed on a monitor. In many cases, the mapping function and a treatment function (e.g., ablation) are provided by a single catheter or group of catheters such that the mapping catheter also operates as a treatment (e.g., ablation) catheter at the same time. Mapping software <NUM> interfaces with catheter <NUM> to perform the mapping operations as described in further detail herein.

In support of the system <NUM> detecting, diagnosing, and/or treating cardiac conditions, the catheter <NUM> can be navigated by the physician <NUM> into the heart <NUM> of the patient <NUM> lying on the bed <NUM>. For instance, the physician <NUM> can insert the shaft <NUM> through the sheath <NUM>, while manipulating a distal end <NUM> of the catheter basket <NUM> using the manipulator <NUM>. The catheter <NUM> can be inserted through the sheath <NUM> in a collapsed state and can be then expanded within the heart <NUM>.

Generally, electrical activity at a point in the heart <NUM> may be typically measured by advancing the catheter <NUM> to that point in the heart <NUM>, contacting the tissue with the one or more electrodes <NUM> and acquiring data at that point.

The catheter <NUM>, includes a plurality of flexible splines <NUM> and a plurality of electrodes <NUM> disposed on each of the flexible splines <NUM>. The catheter <NUM> is configured to obtain biometric data, such as electrical signals of an intra-body organ (e.g., the heart <NUM>), and/or to ablate tissue areas of thereof (e.g., a cardiac chamber of the heart <NUM>). Note that the electrodes <NUM> are representative of any like elements, such as metallic elements, tracking coils, piezoelectric transducer, electrodes, or combination of elements configured to ablate the tissue areas or to obtain the biometric data.

Biometric data (e.g., patient biometrics, patient data, or patient biometric data) can include one or more of local activation times (LATs), electrical activity, topology, bipolar mapping, reference activity, ventricle activity, dominant frequency, impedance, or the like. The LAT can be a point in time of a threshold activity corresponding to a local activation, calculated based on a normalized initial starting point. Electrical activity can be any applicable electrical signals that can be measured based on one or more thresholds and can be sensed and/or augmented based on signal to noise ratios and/or other filters. A topology can correspond to the physical structure of a body part or a portion of a body part and can correspond to changes in the physical structure relative to different parts of the body part or relative to different body parts.

Examples of biometric data include, but are not limited to, patient identification data, IC ECG data, bipolar intracardiac reference signals, anatomical and electrical measurements, trajectory information, body surface (BS) ECG data, historical data, blood pressure data, ultrasound signals, radio signals, audio signals, a two- or three-dimensional image data, blood glucose data, and temperature data. The biometrics data can be used, generally, to monitor, diagnosis, and treatment any number of various diseases, such as cardiovascular diseases (e.g., arrhythmias, cardiomyopathy, and coronary artery disease) and autoimmune diseases (e.g., type I and type II diabetes). Note that BS ECG data can include data and signals collected from electrodes on a surface of a patient, IC ECG data can include data and signals collected from electrodes within the patient, and ablation data can include data and signals collected from tissue that has been ablated. Further, BS ECG data, IC ECG data, and ablation data, along with catheter electrode position data, can be derived from one or more procedure recordings.

For example, the catheter <NUM> can use the electrodes <NUM> to implement intravascular ultrasound and/or MRI catheterization to image the heart <NUM> (e.g., obtain and process the biometric data). Inset <NUM> shows the catheter <NUM> in an enlarged view, inside a cardiac chamber of the heart <NUM>.

The catheter <NUM> is a basket catheter. The basket catheter can be designed such that when deployed into a patient's body, its electrodes can be held in intimate contact against an endocardial surface. As an example, a basket catheter can be inserted into a lumen, such as a pulmonary vein ("PV"). The basket catheter can be inserted into the PV with proximal end at maximal distance from distal end, such that the basket catheter does not occupy its maximum volume while being inserted into the PV. The basket catheter can expand by moving proximal end towards distal end while inside the PV, such that those electrodes on the basket catheter are in contact with an entire circular section of the PV. Such contact with an entire circular section of the PV, or any other lumen, can enable efficient imaging and/or ablation.

According to other examples, body patches and/or body surface electrodes may also be positioned on or proximate to a body of the patient <NUM>. The catheter <NUM> with the one or more electrodes <NUM> can be positioned within the body (e.g., within the heart <NUM>) and a position of the catheter <NUM> can be determined by the system <NUM> based on signals transmitted and received between positions sensors of the catheter <NUM> and the body patches and/or body surface electrodes. Additionally, the electrodes <NUM> can sense the biometric data from within the body of the patient <NUM>, such as within the heart <NUM> (e.g., the electrodes <NUM> sense the electrical potential of the tissue in real time). The biometric data can be associated with the determined position of the catheter <NUM> such that a rendering of the patient's body part (e.g., the heart <NUM>) can be displayed and show the biometric data overlaid on a shape of the body part. The mapping software <NUM> assists with determining position of the electrodes <NUM>, to assist with obtaining the biometric data.

The catheter <NUM> and other items of the system <NUM> can be connected to the console <NUM>. The console <NUM> can include any computing device, which employs the mapping software <NUM>. According to an exemplary embodiment, the console <NUM> includes the one or more processors <NUM> (any computing hardware) and the memory <NUM> (any non-transitory tangible media), where the one or more processors <NUM> execute computer instructions with respect to the mapping software <NUM> and the memory <NUM> stores these instructions for execution by the one or more processors <NUM>. For instance, the console <NUM> can be configured to receive and/or store the biometric data on a database of the memory <NUM>, process the biometric data, and determine if a given tissue area conducts electricity.

In an example, the console <NUM> can be any computing device, as noted herein, including software (e.g., the mapping software <NUM>) and/or hardware (e.g., the processor <NUM> and the memory <NUM>), such as a general-purpose computer, with suitable front end and interface circuits for transmitting and receiving signals to and from the catheter <NUM>, as well as for controlling the other components of the system <NUM>. For example, the front end and interface circuits include input/output (I/O) communication interfaces that enables the console <NUM> to receive signals from and/or transfer signals to the at least one electrode <NUM>. The console <NUM> can include real-time noise reduction circuitry typically configured as a field programmable gate array (FPGA), followed by an analog-to-digital (A/D) ECG or electrocardiograph/electromyogram (EMG) signal conversion integrated circuit. The console <NUM> can pass the signal from an A/D ECG or EMG circuit to another processor and/or can be programmed to perform one or more functions disclosed herein.

The display <NUM>, which can be any electronic device for the visual presentation of the biometric data, is connected to the console <NUM>. According to an exemplary embodiment, during a procedure, the console <NUM> can facilitate on the display <NUM> a presentation of a body part rendering to the physician <NUM> and store data representing the body part rendering in the memory <NUM>. For instance, maps depicting motion characteristics can be rendered/constructed based on the trajectory information sampled at a sufficient number of points in the heart <NUM>. As an example, the display <NUM> can include a touchscreen that can be configured to accept inputs from the physician <NUM>, in addition to presenting the body part rendering.

In some embodiments, the physician <NUM> can manipulate the elements of the system <NUM> and/or the body part rendering using one or more input devices, such as a touch pad, a mouse, a keyboard, a gesture recognition apparatus, or the like. For example, an input device can be used to change a position of the catheter <NUM>, such that rendering is updated. Note that the display <NUM> can be located at a same location or a remote location, such as a separate hospital or in separate healthcare provider networks.

In one example, to obtain electrode position data for the electrodes <NUM>, the console <NUM> can be connected, by a cable, to body surface ("BS") electrodes, which include adhesive skin patches affixed to the patient <NUM>. More particularly, the processor <NUM> can determine position coordinates of the electrodes <NUM> inside the body part (e.g., the heart <NUM>) of the patient <NUM>. The position coordinates may be based on impedances or electromagnetic fields measured between the body surface electrodes and the electrode <NUM> of the catheter <NUM> or other electromagnetic components such as position sensors disposed within the catheter basket <NUM>. Additionally, or alternatively, location pads, which generate magnetic fields used for navigation, may be located on a surface of the bed <NUM> and may be separate from the bed <NUM>. The biometric data can be transmitted to the console <NUM> and stored in the memory <NUM>. Alternatively, or in addition, the biometric data may be transmitted to a server, which may be local or remote, using a network as further described herein.

According to one or more exemplary embodiments, the catheter <NUM> may be configured to ablate tissue areas of a cardiac chamber of the heart <NUM>. For instance, ablation electrodes, such as the at least one electrode <NUM>, may be configured to provide energy to tissue areas of an intra-body organ (e.g., the heart <NUM>). The energy may be thermal energy and may cause damage to the tissue area starting from the surface of the tissue area and extending into the thickness of the tissue area. The biometric data with respect to ablation procedures (e.g., ablation tissues, ablation locations, etc.) can be considered ablation data.

A catheter ablation-based treatment may include mapping the electrical properties of heart tissue, especially the endocardium and the heart volume, and selectively ablating cardiac tissue by application of energy. Electrical or cardiac mapping (e.g., implemented by any electrophysiological cardiac mapping system and technique described herein) includes creating a map of electrical potentials (e.g., a voltage map) of the wave propagation along the heart tissue or a map of arrival times (e.g., a LAT map) to various tissue located points. Electrical or cardiac mapping (e.g., a cardiac map) may be used for detecting local heart tissue dysfunction. Ablations, such as those based on cardiac mapping, can cease or modify the propagation of unwanted electrical signals from one portion of the heart <NUM> to another.

The ablation process damages the unwanted electrical pathways by formation of non-conducting lesions. Various energy delivery modalities have been disclosed for forming lesions, and include use of microwave, laser and more commonly, radiofrequency energies to create conduction blocks along the cardiac tissue wall. Another example of an energy delivery technique includes irreversible electroporation (IRE), which provides high electric fields that damage cell membranes. In a two-step procedure (e.g., mapping followed by ablation) electrical activity at points within the heart <NUM> is typically sensed and measured by advancing the catheter <NUM> containing one or more electrical sensors (e.g., electrodes <NUM>) into the heart <NUM> and obtaining/acquiring data at a multiplicity of points (e.g., as biometric data generally, or as ECG data specifically). This ECG data is then utilized to select the endocardial target areas, at which ablation is to be performed. The mapping software <NUM> assists with these steps by estimating position of the electrodes <NUM>.

Among other things, the mapping software <NUM> maps position of the electrodes <NUM> of the catheter <NUM>. The catheter <NUM> has position tracking elements on proximal and distal ends of the catheter basket <NUM>, but the electrodes <NUM> themselves do not have associated position sensors. Further, the electrodes <NUM> are disposed on flexible splines <NUM> which bend based both on relative positions of the proximal and distal ends of the catheter basket <NUM> as well as deflection of the entire catheter <NUM> with respect to the shaft <NUM>. Thus, the mapping software <NUM> performs operations to determine the shape and positions of the splines <NUM> based on the detected positions and orientations of the proximal and distal ends of the catheter basket <NUM> as well as the deflection angle of the catheter basket <NUM>. The mapping software <NUM> generates Bezier curves to represent the shape, position, and/or deflection of the splines <NUM> and obtains positions of the electrodes <NUM> based on the shape, position, and/or deflection. Additional details follow.

Turning now to <FIG>, a diagram of a system <NUM> in which one or more features of the disclosed subject matter can be implemented is illustrated according to one or more exemplary embodiments. The system <NUM> includes, in relation to a patient <NUM> (e.g., an example of the patient <NUM> of <FIG>), an apparatus <NUM>, a local computing device <NUM>, a remote computing system <NUM>, a first network <NUM>, and a second network <NUM>. Further, the apparatus <NUM> includes a catheter <NUM> (e.g., an example of the catheter <NUM> of <FIG>), a processor <NUM>, one or more position system(s) <NUM>, a memory <NUM>, and a transceiver <NUM>, as well as mapping software <NUM>.

The apparatus <NUM> can be an example of the system <NUM> of <FIG>, where the apparatus <NUM> can include both components that are internal to the patient and components that are external to the patient. While a single apparatus <NUM> is shown in <FIG>, example systems may include a plurality of apparatuses.

Accordingly, the apparatus <NUM>, the local computing device <NUM>, and/or the remote computing system <NUM> can be programed to execute computer instructions with respect to the mapping software <NUM>. As an example, the memory <NUM> stores these instructions for execution by the processor <NUM> so that the apparatus <NUM> can receive and process the biometric data via the catheter <NUM>. In this way, the processor <NUM> and the memory <NUM> are representative of processors and memories of the local computing device <NUM> and/or the remote computing system <NUM>. It is possible for some or all of the mapping software <NUM> to exist and be executed by any of the apparatus <NUM>, local computing device <NUM>, and remote computing system <NUM>.

The networks <NUM> and <NUM> can be a wired network, a wireless network, or include one or more wired and wireless networks. According to an embodiment, the network <NUM> is an example of a short-range network (e.g., local area network (LAN), or personal area network (PAN)). Information can be sent, via the network <NUM>, between the apparatus <NUM> and the local computing device <NUM> using any one of various short-range wireless communication protocols, such as Bluetooth, Wi-Fi, Zigbee, Z-Wave, near field communications (NFC), ultra-band, Zigbee, or infrared (IR). Further, the network <NUM> is an example of one or more of an Intranet, a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a direct connection or series of connections, a cellular telephone network, or any other network or medium capable of facilitating communication between the local computing device <NUM> and the remote computing system <NUM>. Information can be sent, via the network <NUM>, using any one of various long-range wireless communication protocols (e.g., TCP/IP, HTTP, <NUM>, <NUM>/LTE, or <NUM>/New Radio). Note that for either network <NUM> and <NUM> wired connections can be implemented using Ethernet, Universal Serial Bus (USB), RJ-<NUM> or any other wired connection and wireless connections can be implemented using Wi-Fi, WiMAX, and Bluetooth, infrared, cellular networks, satellite or any other wireless connection methodology.

In operation, the apparatus <NUM> can continually or periodically obtain, monitor, store, process, and communicate via network <NUM> the biometric data associated with the patient <NUM> and the position data of the catheter <NUM> (e.g., for the catheter electrodes <NUM> of the catheter basket <NUM>). Further, the apparatus <NUM>, local computing device <NUM>, and the remote computing system <NUM> are in communication through the networks <NUM> and <NUM> (e.g., the local computing device <NUM> can be configured as a gateway between the apparatus <NUM> and the remote computing system <NUM>). For instance, the apparatus <NUM> can be an example of the system <NUM> of <FIG> configured to communicate with the local computing device <NUM> via the network <NUM>. The local computing device <NUM> can be, for example, a stationary/standalone device, a base station, a desktop/laptop computer, a smart phone, a smartwatch, a tablet, or other device configured to communicate with other devices via networks <NUM> and <NUM>. The remote computing system <NUM>, implemented as a physical server on or connected to the network <NUM> or as a virtual server in a public cloud computing provider (e.g., Amazon Web Services (AWS) ®) of the network <NUM>, can be configured to communicate with the local computing device <NUM> via the network <NUM>. Thus, the biometric data associated with the patient <NUM> can be communicated throughout the system <NUM>.

Elements of the apparatus <NUM> are now described. The catheter <NUM> is the catheter <NUM> of <FIG>. The processor <NUM>, in executing the mapping software <NUM>, can be configured to receive, process, and manage the biometric data acquired by the catheter <NUM>, and communicate the biometric data to the memory <NUM> for storage (e.g., on a database therein) and/or across the network <NUM> via the transceiver <NUM> (e.g., to a database thereof). Biometric data from one or more other apparatuses <NUM> can also be received by the processor <NUM> through the transceiver <NUM>. The one or more position system(s) <NUM> include elements for detecting position of one or more elements of the catheter <NUM>, such as the proximal end and distal end of the catheter basket <NUM>. In some examples, the one or more position system(s) <NUM> includes a magnetic position detection system as described elsewhere herein. In some examples, the magnetic position detection system includes one or more reference electrodes, such as body surface electrodes or electrodes disposed on a bed. The reference electrodes are connected to a processing system (e.g., the processor <NUM>). The reference electrodes communicate with position sensors of the catheter basket <NUM> to assist with determining position of those position sensors. In some examples, the position system(s) <NUM> include one or more other systems for detecting the positions for the catheter <NUM> (such as the positions of the proximal end and distal end of the catheter basket <NUM>). The processor <NUM> interfaces with the position system(s) to obtain position data for the catheter <NUM>. The mapping software <NUM> utilizes the position data to determine position of the electrodes <NUM> as described elsewhere herein.

In some examples, the position sensors <NUM> and <NUM> interface with a position sensing system according to a magnetic position detection technique. In some such examples, each position sensor includes three coils, each oriented in an orthogonal direction. Electrical current passing through each coil of each position sensor generates a magnetic field that is sensed by a location pad. In some examples, the location pad has at least three magnetic field generating corners, each having three orthogonally oriented coils that are configured to generate magnetic fields. Using the location pad, the position system <NUM> senses the magnetic signals emitted by the position sensors <NUM> and <NUM>. The position system <NUM> utilizes the strength of the electrical signal received by the coils in each corner to triangulate the positions of each of the position sensors <NUM> and <NUM>. The position system <NUM> uses the strengths of the signals received with the differently oriented sensors in the location pad to determine the orientation of the position sensors <NUM> and <NUM>.

The memory <NUM> is any non-transitory tangible media, such as magnetic, optical, or electronic memory (e.g., any suitable volatile and/or non-volatile memory, such as random-access memory or a hard disk drive). The memory <NUM> stores the computer instructions for execution by the processor <NUM>. The transceiver <NUM> may include a separate transmitter and a separate receiver. Alternatively, the transceiver <NUM> may include a transmitter and receiver integrated into a single device.

<FIG> illustrates a catheter basket <NUM>, according to an example. The catheter basket <NUM> includes a shaft <NUM> coupled to a proximal end <NUM> of the catheter basket <NUM> and to a distal end <NUM> of a catheter basket <NUM>. Splines <NUM> are coupled to a proximal end <NUM> and a distal end <NUM> of the catheter basket <NUM>. Electrodes <NUM> are disposed on the splines <NUM>. The proximal end <NUM> and distal end <NUM> are movable with respect to each other. A puller element <NUM>, which is coupled to the distal end <NUM> of the catheter basket <NUM>, can be pulled towards the proximal end <NUM> of the catheter basket to move the distal end <NUM> closer to the proximal end <NUM>, or can be pushed from the proximal end <NUM> to move the distal end <NUM> farther from the proximal end <NUM>. Moving the distal end <NUM> with respect to the proximal end <NUM> causes the splines <NUM> to deform. In addition, it is possible for the catheter basket <NUM> to be deflected at an angle with respect to the shaft <NUM> at the proximal end <NUM>. In other words, it is possible for the basket assembly to bend at the proximal end <NUM>, with respect to an "incoming angle" of the shaft <NUM>. For example, when a part of the catheter basket <NUM> such as one or more of the splines <NUM> contacts anatomical structure, the catheter basket <NUM> deflects at an angle with respect to the shaft <NUM> at the proximal end <NUM>. The shape of the splines <NUM> and thus the positions of the electrodes <NUM> thus depends on the relative positions of the proximal end <NUM> and the distal end <NUM>, as well as the angle of deflection of the catheter <NUM> with respect to the shaft <NUM> at the proximal end <NUM>. The proximal end <NUM> and distal end <NUM> each include one or more position sensors (the proximal end position sensor <NUM> and the distal end position sensor <NUM>), so that mapping software <NUM> is able to determine their three-dimensional ("3D") positions directly (e.g., in conjunction with the position system(s) <NUM>). However, the splines <NUM> do not have position sensors and, moreover, can change shape. For this reason, mapping software <NUM> estimates the positions and shapes of the splines <NUM> in order to use that information for mapping or ablation techniques as described herein.

<FIG> illustrates the catheter <NUM> in a deflected configuration. As can be seen, a portion of the shaft after to the proximal end <NUM> (the deflected portion of the shaft <NUM>(<NUM>)) is deflected at an angle with respect to the portion of the shaft prior to the proximal end <NUM> (the undeflected portion of the shaft <NUM>(<NUM>)). The splines <NUM> are bent in a certain way based on the angle of deflection. As shown, the catheter <NUM> is deflected to the right. Thus, the splines <NUM> on the right side experience pressure from the distal end <NUM> and proximal end <NUM> and thus extend further outward from the shaft <NUM> as compared with the splines <NUM> on the left side. The splines <NUM> on the left side are relatively more stretched out and thus are closer to the shaft <NUM> and to each other. The splines <NUM> on the left side are closer together as compared to the splines <NUM> on the right side, which are more spaced apart. The mapping software <NUM> uses these features of the geometry, along with the locations of the splines <NUM>, to determine the shape of the splines <NUM> and the three-dimensional positions of the electrodes <NUM>.

As described, the distal end position sensor <NUM> and proximal end position sensor <NUM> are capable of facilitating determination of the positions of the distal end <NUM> and proximal end <NUM>, respectively. In some examples, the distal end position sensor <NUM> and proximal end position sensor <NUM>, themselves, include mechanisms for determining orientation of the distal end position sensor <NUM> and the proximal end position sensor <NUM>, and thus for determining angle of the shaft <NUM> with respect to the sheath <NUM>. Such angle would simply be the angle reflected by the distal end position sensor <NUM> with respect to the angle reflected by the proximal end position sensor <NUM>. In various examples, the proximal end position sensor <NUM> and distal end position sensor <NUM> include one or more electromagnetic components that emit signals reflective of the orientation of the sensors. A processing element such as the position system(s) <NUM> and/or the mapping software <NUM> is capable of receiving and interpreting the signals to identify the relative angles. In an alternative, one or more force sensors are present on the catheter <NUM>. The one or more force sensors measure force applied to the catheter <NUM> and the direction of that force. A processing element such as the mapping software <NUM> is capable of determining the angle based on the measured force. In an example, the processing element modifies the measured force by a decay factor, reflecting the fact that as more deflection occurs, more force is needed for further deflection, to obtain the angle of deflection. Although several options for determining deflection angle are described, any technically feasible means for determining angle of deflection is possible. The processing element determines the shapes of the splines <NUM> based on the angle of deflection and the positions of the distal end <NUM> and the proximal end <NUM> as described elsewhere herein.

<FIG> illustrates operations for estimating the shape of the splines <NUM>, according to an example. The mapping software <NUM> accepts as input position data <NUM> (e.g., the locations of the proximal end <NUM> and distal end <NUM> of the catheter <NUM> and the deflection angle). The mapping software <NUM> estimates position and shape of the splines <NUM> using Bezier curves, and outputs the estimated electrode positions <NUM>.

More specifically, the mapping software <NUM> receives information indicating the positions of the proximal end <NUM> and distal end <NUM>, as well as the deflection angle. The mapping software <NUM> also accepts as input (e.g., as a set of stored constants or as input from another software module executing in the system <NUM>) the known length of the splines <NUM>, as well as the tangent of the splines <NUM> at the proximal end. The mapping software <NUM> then calculates the Bezier curve defining the shape of the splines <NUM> in the following manner: <MAT>.

In the above equation, B(t) represents the Bezier curve. Value t is the input value to the function B defining the curve. Value t varies along the curve itself and represents the projection of the curve onto a horizontal axis. Value Pi is the i-th Bezier curve control point. The notation <MAT> refers to the binomial coefficients. n is the number of control points and i is the summation index for the summation operation. The polygon formed by connecting the Bezier control points with lines is called the Bezier polygon. The convex hull of the Bezier polygon contains the Bezier curve. P<NUM> and Pn are the coordinates of the proximal end <NUM> and known length of the spline. P<NUM> and Pn-<NUM> are defined by the tangents of the splines <NUM> at the proximal end <NUM> and distal end <NUM>. Mapping software <NUM> selects the other control points based on conservation of energy considerations. It is assumed that when the splines <NUM> bend, they will bend in a manner that uses minimum spring energy.

The mapping software <NUM> determines the control points for the Bezier curve as described and then estimates the shape of the splines <NUM> using the function B(t). Note that the control points do not necessarily lie on the curve but define the curve. The curve order of a Bezier curve is defined as the number of control points minus one.

As stated above, B(t) describes the curve defined by the control points of the Bezier curve. In some examples, the mapping software <NUM> discretizes a calculated curve shape into several "geometric points. " The geometric points define the shape of the splines <NUM>. These geometric points are points that sit on the curve that defines the shape of the splines and, again, are distinct from the control points that parameterize the Bezier curves. Based on the shapes and positions of the splines <NUM>, the mapping software <NUM> determines the positions of the electrodes <NUM>. For example, the mapping software <NUM> knows how far along each splines <NUM> each electrode <NUM> lies. The mapping software <NUM> the shapes of the splines <NUM>, the mapping software <NUM>.

In some examples, the mapping software <NUM> incorporates the estimated positions of the electrodes <NUM> into the mapping and/or ablation operations. In some examples, the mapping software <NUM> or other software uses the estimated positions to draw the electrodes onto a screen or image for viewing by a human operator. In some examples, this image is combined with other imagery to illustrate the electrodes <NUM> and other equipment such as the remainder of the catheter <NUM> in the context of a clinical environment such as what is shown in <FIG>. In some examples, the mapping software <NUM> also includes the estimated shapes of the splines <NUM> in the display, so that the display output illustrates the positions and shapes of the splines <NUM> as well as the positions of the electrodes <NUM> disposed on those splines <NUM>. In various examples, being able to determine the positions of the electrodes <NUM> facilitates mapping and ablation operations. More specifically, with the positions of the electrodes <NUM>, it is possible to accurately map the locations of actions performed with the electrodes <NUM> to positions relative to anatomical structures. This information thus allows accuracy for a doctor or for a computer system involved with a procedure. In an example where mapping is occurring, the mapping software <NUM> obtains measurements with the electrodes <NUM> that reflect aspects of nearby anatomy being mapped. In examples, these measurements reflect relative distance or position of anatomical structures to the electrodes <NUM>. By knowing the positions of the electrodes <NUM>, the mapping software <NUM> is able to accurately determine geometric features of the anatomical structures. More specifically, the mapping software <NUM> determines geometric features of the anatomical structures by combining the information sensed with the electrodes <NUM> about the relative geometry of anatomical structures with the information of the estimated electrode <NUM> positions to obtain the geometry of the anatomical structures.

<FIG> illustrate aspects of processing for estimating shapes of individual splines <NUM>, according to an example. <FIG> illustrates an estimated spline shape <NUM>, according to an example. In addition, geometry points <NUM> and Bezier curve control points <NUM> are illustrated as well. Endpoint locations <NUM> (e.g., positions of the proximal end <NUM> and distal end <NUM>) illustrate the endpoints of the splines <NUM>.

The mapping software <NUM> determines the control points <NUM> of the Bezier curve in any technically feasible manner, such as in a manner described herein. More specifically, the mapping software <NUM> calculates the control points <NUM> based on the relative locations of the endpoint locations <NUM> as well as the deflection angle of the catheter <NUM>. Then, the mapping software <NUM> generates the geometry points <NUM> based on the control points <NUM>. The geometry points <NUM> define the actual shape of the curve. In some implementations, the mapping software <NUM> also utilizes the geometry points <NUM> to assist with mapping and/or ablation operations. In some examples, the mapping software <NUM> determines the positions of the electrodes <NUM> disposed on the splines <NUM> based on the estimated shapes and positions of the splines <NUM>, and utilizes the electrode positions for the mapping and/or ablation operations. In some implementations, the mapping software <NUM> or other software or hardware uses the geometry points <NUM> to generate an image, which can be used to display the shapes and positions of the splines <NUM> and/or the positions of the electrodes <NUM>.

<FIG> illustrates an estimated spline shape <NUM> that is different than the estimated spline shape <NUM> of <FIG>. In <FIG>, the angle of deflection of the catheter <NUM> is different than the angle in <FIG>. Thus, the estimated spline shape <NUM> is different than in <FIG>. The positions of the Bezier curve control points define the curve, and the curve is shown as falling along a set of geometry points <NUM>.

Referring back to <FIG>, the mapping software <NUM> utilizes the tangents of the splines <NUM> at the proximal end and length of the spline, as well as the positions of the proximal end and distal end, to determine the shapes of the splines <NUM> using Bezier curves. In <FIG>, a subject spline <NUM> is illustrated as an example, to illustrate aspects of the technique. However, it should be understood that in various implementations, the mapping software <NUM> applies the described technique to one, more than one, or all splines <NUM> of a catheter basket <NUM> to determine shapes of those splines <NUM> and thus the positions of the electrodes <NUM> on those splines <NUM>.

According to the invention, the mapping software <NUM> generates a Bezier curve that describes the shape and three-dimensional positions of the splines <NUM>. The Bezier curve is a fourth order Bezier curve that accepts at least four constraints to generate the control points. The four constraints include the position of the distal end of the spline (shown as the distal end position <NUM> for the subject spline <NUM>), the position of the proximal end of the spline (shown as the proximal end position <NUM> for the subject spline <NUM>), the known length of the spline, and the tangent of the spline at the proximal end (shown as proximal end tangent <NUM> for subject spline <NUM>). Based on the above four constraints, the mapping software <NUM> determines the Bezier curve control points. The mapping software <NUM> determines the shape of the splines <NUM> for which the control points are determined as disclosed elsewhere herein (e.g., according to the equation provided above). Using this shape and the positions of the proximal and distal ends of the splines (which are, e.g., determined based on the positions detected via the distal end position sensor <NUM> and proximal end position sensor <NUM>), the mapping software <NUM> determines the positions of the splines <NUM> within the surrounding three-dimensional space (e.g., the three-dimensional space of the heard <NUM> or other anatomical structure(s)).

The mapping software <NUM> determines the positions of the electrodes <NUM> on each spline <NUM> for which the shape and position has been determined, based on the positions and shapes of the splines <NUM>. In an example, the mapping software <NUM> knows how far along each spline <NUM> the electrodes are places. For example, the mapping software <NUM> is provided with information that the electrodes are placed at particular distances along the splines <NUM>. These distances may be expressed in any technically feasible manner, which as with a percentage of the length of the spline <NUM>. In an example, the electrodes are placed every <NUM>% increment along the spline <NUM>. The mapping software <NUM> may use any other technically feasible technique to associate the positions of the electrodes <NUM> with positions along the splines <NUM>.

The mapping software <NUM> determines the three-dimensional position of each electrode <NUM> based on this association between the positions of the electrodes <NUM> and the positions of the splines <NUM>, and based on the shape and position of the splines <NUM> determined using the Bezier curves. In an example, the Bezier curve formula defines a position B with respect to a projected-axis coordinate t. Thus, in some examples, the mapping software <NUM> determines the position of an electrode <NUM> in three-dimensional space, given the position along the spline <NUM> at which the electrode is located. For example, for an electrode that is located <NUM>% of the way from the proximal end to the distal end, the mapping software <NUM> uses <NUM>% as the t coordinate, to determine the on-curve coordinate B for that electrode. In some examples, the technique of determine electrode <NUM> position based on the distance along the spline <NUM> of the electrode and the shape and position of the electrode <NUM> is referred to herein as interpolating. For example, it may sometimes be stated that the mapping software <NUM> determines the position of the electrode <NUM> by interpolating the curve of the spline <NUM> according to the position along the spline <NUM> that the electrode <NUM> lies. The mapping software <NUM> then transforms this coordinate based on the location of the spline <NUM> in three-dimensional space (e.g., the proximal end location and distal end location) to determine the location of the electrode <NUM> in three-dimensional space. The mapping software <NUM> performs these operations for one, more than one, or all splines <NUM> of a catheter basket <NUM> to determine the positions for one, more than one, or all electrodes <NUM> of the catheter basket <NUM>.

It is sometimes stated that the deflection angle is considered in determining the positions and/or shapes of the splines <NUM>. The deflection angle determines the tangent of the distal end (e.g., distal end tangent <NUM>), since the splines <NUM> bend as the distal portion of the shaft <NUM>(<NUM>) bends. Thus, since the Bezier curve control points are determined based at least in part on the spline tangent at the distal end <NUM>, the Bezier curve control points are determined based at least in part on the deflection angle <NUM>.

Once found, the apparatus <NUM> (e.g., in conjunction with the local computing device <NUM> and/or the remote computing system <NUM>) utilizes the electrode <NUM> positions to perform mapping and/or ablation procedures. With the electrode <NUM> positions, the system <NUM> is able to place the electrodes <NUM> in the three-dimensional space of surrounding anatomical structures, which allows for the ablation and/or mapping procedures to proceed using this information. For example, knowing the position of the electrodes <NUM> allows electrical signals obtained via the electrodes <NUM> that indicate proximity to anatomical structures to be converted to positions of the anatomical structures. Additionally, for an ablation procedure, knowing the positions of the electrodes <NUM> in three-dimensional space allows for knowledge of what portions of the anatomical structures is to be ablated.

<FIG> illustrate operations for utilizing Bezier curves to estimate spline shape, according to an example. <FIG> illustrates a spline <NUM> in an undeflected position. <FIG> illustrates a spline <NUM> in a deflected position. In <FIG>, the spline <NUM> is in an undeflected position. This means that the angle <NUM> between the incoming shaft <NUM> and the ray <NUM> between the proximal end <NUM> and the distal end <NUM> is <NUM>. In <FIG>, the spline <NUM> is in a deflected position. This means that the angle <NUM> between the incoming shaft <NUM> and the ray <NUM> between the proximal end <NUM> and the distal end <NUM> is an angle other than <NUM>. In both <FIG>, points C0 through C3 represent the Bezier curve control points.

As stated elsewhere herein, the mapping software <NUM> determines the positions of the Bezier curve control points based on the positions of the proximal end <NUM> and the distal end <NUM>, as well as the deflection angle <NUM> and the tangent of the spline <NUM> near to the proximal end <NUM> and known length of the spline. In both <FIG>, the proximal end tangent <NUM> is the tangent of the spline <NUM> at the proximal end <NUM> and the distal end tangent <NUM> is the tangent of the spline <NUM> at the distal end <NUM>. The proximal end tangent <NUM> is in line with and parallel to the incoming shaft <NUM> due to the way the spline <NUM> is fastened to the shaft. At the distal end, the coupling to the spline <NUM> acts as a hinge and thus the distal end tangent <NUM> is able to move as illustrated.

The mapping software <NUM> uses an iterative technique to determine the positions of the Bezier curve control points. Specifically, while C0 and C3 are fixed - that is, these points are the points of the proximal end <NUM> and the distal end <NUM>, respectively - the points C1 and C2 are chosen to further define the curve. The mapping software <NUM> selects point C1 to keep the splint <NUM> lower than a height threshold <NUM> at a distance <NUM> from the proximal end <NUM>. The distance <NUM> is measured along the ray <NUM> between the proximal end <NUM> and the distal end <NUM>. The height <NUM> is perpendicular to that ray <NUM>. The mapping software <NUM> selects point C2 to keep the length of the spline <NUM> to approximately equivalent to the actual length of the spline <NUM> on which the spline <NUM> is modeled. The mapping software <NUM> also selects point C2 to keep the radius of the spline <NUM> below a maximum radius. In sum, the mapping software <NUM> selects points C0 and C3 based on the actual positions of the proximal end <NUM> and the distal end <NUM> and selects points C1 and C2 based on the physical constraints of the tangent of the spline <NUM> at the proximal end <NUM>, the tangent of the spline <NUM> at the distal end <NUM>, the height <NUM>, and the maximum radius. In some examples, the mapping software <NUM> selects points C1 and C2 iteratively. More specifically, the mapping software <NUM> initially selects point C1 arbitrarily along the ray between point C0 and C3, and initially selects the position of point C2 arbitrarily, with the limitation that the spline <NUM> shape is below the radius threshold. The mapping software <NUM> tests the various limitations, including the length of the spline <NUM> and the height <NUM>. If those limitations are not appropriate, then the mapping software <NUM> selects different points for C1 and C2. The limitations are appropriate if the length of the spline <NUM> is within a threshold percentage of the actual length of the physical spline <NUM> and if the height <NUM> is below a predetermined threshold. If the limitations are appropriate, then the mapping software <NUM> has determined a shape for the spline <NUM>. It should be understood that the mapping software <NUM> applies the technique described with respect to <FIG> to multiple splines <NUM> of a catheter, to determine shape and location of those splines <NUM>.

<FIG> is a flow diagram of a method <NUM> for estimating geometry information for a basket catheter, according to an example. Although described with respect to the systems of <FIG>, those of skill in the art will understand that any system, configured to perform the operations of the method <NUM> in any technically feasible order, falls within the scope of the present disclosure.

At step <NUM>, the mapping software <NUM> retrieves mechanical constraints for the basket <NUM> and/or splines <NUM>. In some examples, the mechanical constraints are the tangent of the spline <NUM> at the proximal end and the known length of the spline.

At step <NUM>, the mapping software <NUM> receives endpoint location data and deflection angle for a catheter basket <NUM>. In some examples, the endpoint location data is data that specifies the positions of the proximal end <NUM> and distal end <NUM> of the basket catheter <NUM>. In some examples, the deflection angle indicates the deflection of the basket catheter <NUM> with respect to angle of the shaft <NUM>. In some examples, the mapping software <NUM> receives or determines the tangents of the splines <NUM> at the proximal end <NUM> and at the distal end <NUM>, and in some examples, at least the tangents of the splines <NUM> at the distal end <NUM> are based on the deflection angle <NUM>.

At step <NUM>, the mapping software <NUM> processes the endpoint location data, the tangent of the spline at the proximal end and the estimate length of the spline to calculate Bezier curve control points. As described above, the control points for the Bezier curves define the geometry of the curves, but do not necessarily sit on the curves themselves.

In some examples, the mapping software <NUM> also calculates the geometry points <NUM> that define the estimated shapes of the splines <NUM> based on the Bezier curve control points. While the Bezier curve control points do not sit on the actual curve, but only define that curve, the geometry points <NUM> sit on the curve and define the curve as a collection of points that fall on that curve.

At step <NUM>, the mapping software <NUM> outputs data indicating estimated spline positions and shapes and/or estimated electrode positions. In some examples, the mapping software <NUM> outputs the data for display on a display to be viewed by a user. Alternatively or additionally, the mapping software <NUM> exports this data for use in mapping or ablation procedures.

In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. A computer readable medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

Examples of computer-readable media include electrical signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, optical media such as compact disks (CD) and digital versatile disks (DVDs), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), and a memory stick. A processor in association with software may be used to implement a radio frequency transceiver for use in a terminal, base station, or any host computer.

It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one more other features, integers, steps, operations, element components, and/or groups thereof.

Claim 1:
A computer-implemented method comprising:
receiving endpoint location data from a pair of position sensors mounted on opposite ends of a catheter basket (<NUM>) and receiving spline tangent data (<NUM>), wherein said catheter basket includes a plurality of flexible splines (<NUM>) and a plurality of electrodes (<NUM>) disposed on each of the flexible splines and wherein said endpoint location data and spline tangent data is received while said catheter basket is positioned within a heart chamber, and wherein the spline tangent data includes information indicating a tangent (<NUM>) of a proximal end of a spline (<NUM>) of the catheter basket;
based on said endpoint location data and spline tangent data, calculating fourth order Bezier curve control points (<NUM>);
based on the fourth order Bezier curve control points, determining estimated positions of said plurality of electrodes; and
updating an electro-anatomical map of said heart chamber that is rendered on a display (<NUM>) based on the estimated positions determined.