Patent Description:
The exemplary systems, methods, and interfaces described herein may be configured to assist a user (e.g., a physician) in evaluating a patient and/or evaluating cardiac therapy (e.g., cardiac therapy being performed on a patient during and/or after implantation of cardiac therapy apparatus). In one or more embodiments, the systems, methods, and interfaces may be described as being noninvasive. For example, in some embodiments, the systems, methods, and interfaces may not need, or include, implantable devices such as leads, probes, sensors, catheters, implantable electrodes, etc. to monitor, or acquire, a plurality of cardiac signals from tissue of the patient for use in evaluating the patient and/or cardiac therapy. Instead, the systems, methods, and interfaces may use electrical measurements taken noninvasively using, e.g., a plurality of external electrodes attached to the skin of a patient about the patient's torso. Document <CIT> discloses system with a graphical user interface that can show a graphical representation of a cardiac map that includes reconstructed electrical activity.

One exemplary system may include can include an electrode apparatus. The electrode apparatus can include a plurality of external electrodes to monitor electrical activity from tissue of a patient. The exemplary system can include computing apparatus that include processing circuitry and that is coupled to the electrode apparatus. The computing apparatus can be configured to monitor electrical activity from the patient using the plurality of external electrodes. The computing apparatus can be further configured to provide a model heart representative of the patient's heart based on at least one of a plurality of patient characteristics. The model heart can include a plurality of segments. The computing apparatus can be further configured to map the monitored electrical activity onto the plurality of segments of the model heart. The computing apparatus can be further configured to determine a value of electrical activity for each of a plurality of anatomic regions of the model heart based on the mapped electrical activity. Each of the plurality of anatomic regions comprises a subset of the plurality of segments.

In at least one embodiment, an exemplary method can include monitoring electrical activity from the patient using a plurality of external electrodes on a torso of a patient. The exemplary method can further include providing a model heart representative of the patient's heart based on at least one of a plurality of patient characteristics. The model heart comprises a plurality of segments. The exemplary method can further include mapping the monitored electrical activity onto the plurality of segments of the model heart. The exemplary method can further include determining a value of electrical activity for each of a plurality of anatomic regions of the model heart based on the mapped electrical activity. Each of the plurality of anatomic regions comprises a subset of the plurality of segments.

In at least one embodiment, an exemplary system can include an electrode apparatus. The electrode apparatus can include a plurality of external electrodes to monitor electrical activity from tissue of a patient. The exemplary system can include computing apparatus that include processing circuitry and that is coupled to the electrode apparatus. The computing apparatus can be configured to monitor electrical activity from the patient using the plurality of external electrodes. The computing apparatus can be further configured to provide a model heart representative of the patient's heart based on at least one of a plurality of patient characteristics. The model heart comprises a plurality of anatomic regions. The computing apparatus can be further configured to map the monitored electrical activity onto the plurality of anatomic regions of the model heart. The computing apparatus can be further configured to determine an indication of scar risk based on the monitored electrical activity mapped on the plurality of anatomic regions. The exemplary system can further include a display. The display can include a graphical user interface configured to assist a user in evaluating patient cardiac health. The computing apparatus can be further configured to display on the display the model heart. The computing apparatus can be further configured to display on the display the mapped electrical activity. The computing apparatus can be further configured to display on the display an identification on the model heart of the determined indication of scar risk.

The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.

In the following detailed description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments which may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from (e.g., still falling within) the scope of the disclosure presented hereby.

Exemplary systems and methods shall be described with reference to <FIG>. It will be apparent to one skilled in the art that elements or processes from one embodiment may be used in combination with elements or processes of the other embodiments, and that the possible embodiments of such methods and systems using combinations of features set forth herein is not limited to the specific embodiments shown in the Figures and/or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be recognized that timing of the processes and the size and shape of various elements herein may be modified but still fall within the scope of the present disclosure, although certain timings, one or more shapes and/or sizes, or types of elements, may be advantageous over others.

Various exemplary systems, methods, and interfaces described herein may be configured to use electrode apparatus including external electrodes, display apparatus, and computing apparatus to noninvasively assist a user (e.g., a physician) in the evaluation of a patient's cardiac condition. Cardiac electrical activity can be monitored and/or detected using unipolar electrocardiogram (ECG) recordings using the external electrodes. The electrical activity can be mapped to a model heart by selecting a particular model heart from a plurality of model hearts based on at least one characteristic of the patient. The characteristic of the patient can include at least one of age, gender, height, chest circumference, heart chamber dimensions, ventricular ejection fraction, type of cardiomyopathy, and duration of QRS complex on <NUM>-lead ECG, among other characteristics. The model heart can be divided into anatomic regions and the electrical activity over each of the anatomic regions can be analyzed. For example, the electrical activity over an anatomic region can be averaged for that anatomic region. Adjacent and/or other anatomic regions can be compared and/or analyzed in order to determine a condition of the patient's heart. As an example, two adjacent anatomic regions with particular electrical activity can be determined to experience slow conduction or conduction block conditions. Such electrical activity may be measured and displayed, or conveyed, to someone aiding the patient by a system which acquires the ECG signals and generates various metrics of electrical activation times (e.g., depolarization) and/or peak-to-peak voltage values measured from various ECG locations. Electrical activation times can be representative of depolarization of cardiac tissue that propagates through the torso of the patient.

An exemplary system <NUM> including electrode apparatus <NUM>, display apparatus <NUM>, and computing apparatus <NUM> is depicted in <FIG>. The electrode apparatus <NUM> as shown includes a plurality of electrodes incorporated, or included, within a band wrapped around the chest, or torso, of a patient <NUM>. The electrode apparatus <NUM> is operatively coupled to the computing apparatus <NUM> (e.g., through one or wired electrical connections, wirelessly, etc.) to provide electrical signals from each of the electrodes to the computing apparatus <NUM> for analysis, evaluation, etc. Exemplary electrode apparatus may be described in <CIT>. Further, exemplary electrode apparatus <NUM> will be described in more detail in reference to <FIG>.

Although not described herein, the exemplary system <NUM> may further include imaging apparatus. The imaging apparatus may be any type of imaging apparatus configured to image, or provide images of, at least a portion of the patient in a noninvasive manner. For example, the imaging apparatus may not use any components or parts that may be located within the patient to provide images of the patient except noninvasive tools such as contrast solution. It is to be understood that the exemplary systems, methods, and interfaces described herein may further use imaging apparatus to provide noninvasive assistance to a user (e.g., a physician) for pre-procedural and intra-procedural planning for implantation of a left ventricular (LV) lead or a leadless LV pacer, among other types of implantations. An exemplary leadless LV pacer comprises the MICRI™ commercially available from Medtronic, Inc. located in Minneapolis, MN.

For example, the exemplary systems, methods, and interfaces may provide image guided navigation that may be used to navigate leads including electrodes, leadless electrodes, wireless electrodes, catheters, etc., within the patient's body while also providing noninvasive cardiac therapy evaluation including pre-procedural and/or intra-procedural planning for cardiac implantation of a lead or leadless pacer. Exemplary systems and methods that use imaging apparatus and/or electrode apparatus may be described in <CIT> and entitled "Implantable Electrode Location Selection," <CIT> and entitled "Implantable Electrode Location Selection," <CIT> and entitled "Systems, Methods, and Interfaces for Identifying Effective Electrodes," <CIT> and entitled "Systems, Methods, and Interfaces for Identifying Optical Electrical Vectors.

Exemplary imaging apparatus may be configured to capture x-ray images and/or any other alternative imaging modality. For example, the imaging apparatus may be configured to capture images, or image data, using isocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computed tomography (CT), multi-slice computed tomography (MSCT), magnetic resonance imaging (MRI), high frequency ultrasound (HIFU), optical coherence tomography (OCT), intra-vascular ultrasound (IVUS), two dimensional (2D) ultrasound, three dimensional (3D) ultrasound, four dimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc. Further, it is to be understood that the imaging apparatus may be configured to capture a plurality of consecutive images (e.g., continuously) to provide video frame data. In other words, a plurality of images taken over time using the imaging apparatus may provide video frame, or motion picture, data. Additionally, the images may also be obtained and displayed in two, three, or four dimensions. In more advanced forms, four-dimensional surface rendering of the heart or other regions of the body may also be achieved by incorporating heart data or other soft tissue data from a map or from pre-operative image data captured by MRI, CT, or echocardiography modalities. Image datasets from hybrid modalities, such as positron emission tomography (PET) combined with CT, or single photon emission computer tomography (SPECT) combined with CT, could also provide functional image data superimposed onto anatomical data, e.g., to be used to navigate cardiac implantation apparatus within the heart or other areas of interest.

Systems and/or imaging apparatus that may be used in conjunction with the exemplary systems and method described herein are described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

The display apparatus <NUM> and the computing apparatus <NUM> may be configured to display and analyze data such as, e.g., electrical signals (e.g., electrocardiogram data), cardiac activation times, peak-to-peak data, cardiac information representative of at least one of mechanical cardiac functionality and electrical cardiac functionality, etc. Cardiac information may include, e.g., electrical heterogeneity information or electrical dyssynchrony information, surrogate electrical activation information or data, etc. that is generated using electrical signals gathered, monitored, or collected, using the electrode apparatus <NUM>. In at least one embodiment, the computing apparatus <NUM> may be a server, a personal computer, or a tablet computer. The computing apparatus <NUM> may be configured to receive input from input apparatus <NUM> and transmit output to the display apparatus <NUM>. Further, the computing apparatus <NUM> may include data storage that may allow for access to processing programs or routines and/or one or more other types of data, e.g., for driving a graphical user interface configured to noninvasively assist a user in evaluating during pre-procedural and/or intra-procedural planning for cardiac implantation of a lead or leadless pacer.

The computing apparatus <NUM> may be operatively coupled to the input apparatus <NUM> and the display apparatus <NUM> to, e.g., transmit data to and from each of the input apparatus <NUM> and the display apparatus <NUM>. For example, the computing apparatus <NUM> may be electrically coupled to each of the input apparatus <NUM> and the display apparatus <NUM> using, e.g., analog electrical connections, digital electrical connections, wireless connections, bus-based connections, network-based connections, internet-based connections, etc. As described further herein, a user may provide input to the input apparatus <NUM> to manipulate, or modify, one or more graphical depictions displayed on the display apparatus <NUM> and to view and/or select one or more pieces of information related to the cardiac implantation and/or therapy.

Although as depicted the input apparatus <NUM> is a keyboard, it is to be understood that the input apparatus <NUM> may include any apparatus capable of providing input to the computing apparatus <NUM> to perform the functionality, methods, and/or logic described herein. For example, the input apparatus <NUM> may include a mouse, a trackball, a touchscreen (e.g., capacitive touchscreen, a resistive touchscreen, a multi-touch touchscreen, etc.), etc. Likewise, the display apparatus <NUM> may include any apparatus capable of displaying information to a user, such as a graphical user interface <NUM> including cardiac information, textual instructions, graphical depictions of electrical activation information, graphical depictions of anatomy of a human heart, two-dimensional and three-dimensional model hearts for a plurality of different model humans, two-dimensional and three-dimensional model torsos for a plurality of different model humans, cardiac conduction indicators, scar risk indicators, images or graphical depictions of the patient's heart, graphical depictions of locations of one or more electrodes, graphical depictions of a human torso, images or graphical depictions of the patient's torso, graphical depictions or actual images of implanted electrodes and/or leads, etc. Further, the display apparatus <NUM> may include a liquid crystal display, an organic light-emitting diode screen, a touchscreen, a cathode ray tube display, etc..

The processing programs or routines stored and/or executed by the computing apparatus <NUM> may include programs or routines for computational mathematics, image construction algorithms, inverse problem processes for image and/or data projection, two-dimensional and three-dimensional image and/or data projection processes, matrix mathematics, dispersion determinations (e.g. standard deviations, variances, ranges, interquartile ranges, mean absolute differences, average absolute deviations, etc.), filtering algorithms, maximum value determinations, minimum value determinations, threshold determinations, moving windowing algorithms, decomposition algorithms, compression algorithms (e.g., data compression algorithms), calibration algorithms, signal processing algorithms (e.g., various filtering algorithms, Fourier transforms, fast Fourier transforms, etc.), standardization algorithms, comparison algorithms, vector mathematics, or any other processing required to implement one or more exemplary methods and/or processes described herein. Data stored and/or used by the computing apparatus <NUM> may include, for example, electrical signal/waveform data from the electrode apparatus <NUM>, one or metrics generated, or derived, from electrical signal/waveform data from the electrode apparatus <NUM> (e.g., peak-to-peak values, activation times, metrics of cardiac electrical heterogeneity and desynchrony, etc.), dispersions signals, windowed dispersions signals, parts or portions of various signals, electrical activation times from the electrode apparatus <NUM>, graphics (e.g., graphical elements, icons, buttons, windows, dialogs, pull-down menus, graphic areas, graphic regions, 3D graphics, etc.), graphical user interfaces, results from one or more processing programs or routines employed according to the disclosure herein (e.g., electrical signals, cardiac information, etc.), or any other data that may be necessary for carrying out the one and/or more processes or methods described herein.

In one or more embodiments, the exemplary systems, methods, and interfaces may be implemented using one or more computer programs executed on programmable computers, such as computers that include, for example, processing capabilities, data storage (e.g., volatile or non-volatile memory and/or storage elements), input devices, and output devices. Program code and/or logic described herein may be applied to input data to perform functionality described herein and generate desired output information. The output information may be applied as input to one or more other devices and/or methods as described herein or as would be applied in a known fashion.

The one or more programs used to implement the systems, methods, and/or interfaces described herein may be provided using any programmable language, e.g., a high-level procedural and/or object orientated programming language that is suitable for communicating with a computer system. Any such programs may, for example, be stored on any suitable device, e.g., a storage media, that is readable by a general or special purpose program running on a computer system (e.g., including processing apparatus) for configuring and operating the computer system when the suitable device is read for performing the procedures described herein. In other words, at least in one embodiment, the exemplary systems, methods, and/or interfaces may be implemented using a computer readable storage medium, configured with a computer program, where the storage medium so configured causes the computer to operate in a specific and predefined manner to perform functions described herein. Further, in at least one embodiment, the exemplary systems, methods, and/or interfaces may be described as being implemented by logic (e.g., object code) encoded in one or more non-transitory media that includes code for execution and, when executed by a processor, is operable to perform operations such as the methods, processes, and/or functionality described herein.

The computing apparatus <NUM> may be, for example, any fixed or mobile computer system (e.g., a controller, a microcontroller, a personal computer, minicomputer, tablet computer, etc.) and may be generally described as including processing circuitry. The exact configuration of the computing apparatus <NUM> is not limiting, and essentially any device capable of providing suitable computing capabilities and control capabilities (e.g., graphics processing, etc.) may be used. As described herein, a digital file may be any medium (e.g., volatile or non-volatile memory, a CD-ROM, a punch card, magnetic recordable medium such as a disk or tape, etc.) containing digital bits (e.g., encoded in binary, trinary, etc.) that may be readable and/or writeable by computing apparatus <NUM> described herein. Also, as described herein, a file in user-readable format may be any representation of data (e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers, graphically, etc.) presentable on any medium (e.g., paper, a display, etc.) readable and/or understandable by a user.

In view of the above, it will be readily apparent that the functionality as described in one or more embodiments according to the present disclosure may be implemented in any manner as would be known to one skilled in the art. As such, the computer language, the computer system, or any other software/hardware which is to be used to implement the processes described herein shall not be limiting on the scope of the systems, processes or programs (e.g., the functionality provided by such systems, processes or programs) described herein.

Data generated using electrode apparatus <NUM> as shown in <FIG> and in <FIG> may be useful to evaluate a pre-procedural and/or intra-procedural plan for cardiac implantation and/or therapy. For example, surrogate electrical activation information or data of one or more regions of a patient's heart may be monitored, or determined, using the electrode apparatus <NUM>. More specifically, the exemplary electrode apparatus <NUM> may be configured to measure body-surface potentials, or torso-surface potentials, of a patient <NUM>. As shown in <FIG>, the exemplary electrode apparatus <NUM> may include a set, or array, of electrodes <NUM>, a strap <NUM>, and interface/amplifier circuitry <NUM>. The electrodes <NUM> may be attached, or coupled, to the strap <NUM> and the strap <NUM> may be configured to be wrapped around the torso of a patient <NUM> such that the electrodes <NUM> surround the patient's heart. As further illustrated, the electrodes <NUM> may be positioned around the circumference of a patient <NUM>, including the posterior, lateral, posterolateral, anterolateral, and anterior locations of the torso of a patient <NUM>.

Further, the electrodes <NUM> may be electrically connected to interface/amplifier circuitry <NUM> via wired connection <NUM>. The interface/amplifier circuitry <NUM> may be configured to amplify the signals from the electrodes <NUM> and provide the signals to the computing apparatus <NUM>. Other exemplary systems may use a wireless connection to transmit the signals sensed by electrodes <NUM> to the interface/amplifier circuitry <NUM> and, in tum, the computing apparatus <NUM>, e.g., as channels of data. For example, the interface/amplifier circuitry <NUM> may be electrically coupled to each of the computing apparatus <NUM> and the display apparatus <NUM> using, e.g., analog electrical connections, digital electrical connections, wireless connections, bus-based connections, network-based connections, internet-based connections, etc..

Although in the example of <FIG> the electrode apparatus <NUM> includes a strap <NUM>, in other examples any of a variety of mechanisms, e.g., tape or adhesives, may be employed to aid in the spacing and placement of electrodes <NUM>. In some examples, the strap <NUM> may include an elastic band, strip of tape, or cloth. In other examples, the electrodes <NUM> may be placed individually on the torso of a patient <NUM>. Further, in other examples, electrodes <NUM> (e.g., arranged in an array) may be part of, or located within, patches, vests, and/or other manners of securing the electrodes <NUM> to the torso of the patient <NUM>.

The electrodes <NUM> may be configured to surround the heart of the patient <NUM> and record, or monitor, the electrical signals associated with the depolarization and repolarization of the heart after the signals have propagated through the torso of a patient <NUM>. Each of the electrodes <NUM> may be used in a unipolar configuration to sense the torso-surface potentials that reflect the cardiac signals. The interface/amplifier circuitry <NUM> may also be coupled to a return or indifferent electrode (not shown) that may be used in combination with each electrode <NUM> for unipolar sensing. In some examples, there may be about <NUM> to about <NUM> electrodes <NUM> spatially distributed around the torso of patient. Other configurations may have more or fewer electrodes <NUM>.

The computing apparatus <NUM> may record and analyze the electrical activity (e.g., torso-surface potential signals) sensed by electrodes <NUM> and amplified/conditioned by the interface/amplifier circuitry <NUM>. The computing apparatus <NUM> may be configured to analyze the signals from the electrodes <NUM> to provide as anterior and posterior electrode signals and surrogate cardiac electrical activation times, e.g., representative of actual, or local, electrical activation times of one or more regions of the patient's heart as will be further described herein. The computing apparatus <NUM> may be configured to analyze the signals from the electrodes <NUM> to provide peak-to-peak values, e.g., representative of actual, or local, peak-to-peak values of one or more regions of the patient's heart as will be further described herein. Further, the electrical signals measured at the left anterior surface location of a patient's torso may be representative, or surrogates, of electrical signals of the left anterior left ventricle region of the patient's heart, electrical signals measured at the left lateral surface location of a patient's torso may be representative, or surrogates, of electrical signals of the left lateral left ventricle region of the patient's heart, electrical signals measured at the left posterolateral surface location of a patient's torso may be representative, or surrogates, of electrical signals of the posterolateral left ventricle region of the patient's heart, and electrical signals measured at the posterior surface location of a patient's torso may be representative, or surrogates, of electrical signals of the posterior left ventricle region of the patient's heart. In one or more embodiments, measurement of activation times can be performed by measuring the period of time between an onset of cardiac depolarization (e.g., onset of QRS complex) and an appropriate fiducial point such as, e.g., a peak value, a minimum value, a minimum slope, a maximum slope, a zero crossing, a threshold crossing, etc..

Additionally, the computing apparatus <NUM> may be configured to provide graphical user interfaces depicting the surrogate electrical activation times obtained using the electrode apparatus <NUM>. Exemplary systems, methods, and/or interfaces may noninvasively use the electrical information collected using the electrode apparatus <NUM> to evaluate a pre-procedural and/or intra-procedural implantation plan for the patient.

<FIG> illustrates another exemplary electrode apparatus <NUM> that includes a plurality of electrodes <NUM> configured to surround the heart of the patient <NUM> and record, or monitor, the electrical signals associated with the depolarization and repolarization of the heart after the signals have propagated through the torso of the patient <NUM>. The electrode apparatus <NUM> may include a vest <NUM> upon which the plurality of electrodes <NUM> may be attached, or to which the electrodes <NUM> may be coupled. In at least one embodiment, the plurality, or array, of electrodes <NUM> may be used to collect electrical information such as, e.g., surrogate electrical activation times. Similar to the electrode apparatus <NUM> of <FIG>, the electrode apparatus <NUM> of <FIG> may include interface/amplifier circuitry <NUM> electrically coupled to each of the electrodes <NUM> through a wired connection <NUM> and be configured to transmit signals from the electrodes <NUM> to computing apparatus <NUM>. As illustrated, the electrodes <NUM> may be distributed over the torso of a patient <NUM>, including, for example, the anterior, lateral, posterolateral, anterolateral, and posterior surfaces of the torso of the patient <NUM>.

The vest <NUM> may be formed of fabric with the electrodes <NUM> attached to the fabric. The vest <NUM> may be configured to maintain the position and spacing of electrodes <NUM> on the torso of the patient <NUM>. Further, the vest <NUM> may be marked to assist in determining the location of the electrodes <NUM> on the surface of the torso of the patient <NUM>. In one or more embodiments, the vest <NUM> may include <NUM> or more anterior electrodes positionable proximate the anterior torso of the patient, and <NUM> or more posterior electrodes positionable proximate the anterior torso of the patient. In some examples, there may be about <NUM> electrodes <NUM> to about <NUM> electrodes <NUM> distributed around the torso of the patient <NUM>, though other configurations may have more or less electrodes <NUM>.

As described herein, the electrode apparatus <NUM> may be configured to measure electrical information (e.g., electrical signals) representing different regions of a patient's heart. For example, activation times of different regions of a patient's heart can be approximated from surface electrocardiogram (ECG) activation times measured using surface electrodes in proximity to surface areas corresponding to the different regions of the patient's heart. That is, the approximation of activation times of the patient's heart can be based on a mapping of activation times from monitored electrical activity being correlated to a model heart and solving an inverse problem to determine an approximate activation time for a region and/or location of the patient's heart, as is described in association with <FIG>. Further, for example, peak-to-peak values of different regions of a patient's heart can be approximated from surface electrocardiogram (ECG) signals measured using surface electrodes in proximity to surface areas corresponding to the different regions of the patient's heart.

The exemplary systems, methods, and interfaces may be used to provide noninvasive assistance to a user in the pre-procedural and/or intra-procedural planning of cardiac implantation for therapy related to a patient's cardiac health or status, and/or the evaluation of cardiac therapy post-implantation by use of the electrode apparatus <NUM> (e.g., cardiac therapy being presently-delivered to a patient during implantation or after implantation). Further, the exemplary systems, methods, and interfaces may be used to assist a user in the planning of cardiac implantation within and/or therapy being delivered to a patient.

Electrical activity monitored by the plurality of external electrodes can be used to solve an inverse problem of electrocardiography. The solution of the inverse problem can be based on a projection of locations at which the torso-surface potentials are measured, monitored by the external electrodes, onto a model torso. The torso-surface potentials can be projected onto locations on the model heart based on a geometric relationship between the model heart and the model torso. As the model heart is selected based on at least one characteristic of a patient, the model torso associated with the model heart can correspond to the physical torso of the patient based on the at least one characteristic of the patient. As an example, a chest circumference of the patient can be used to select the model heart, and thus, the model torso associated with the model heart would correspond to the patient's physical torso based on the chest circumference used. In this way, solving the inverse problem can include estimating potentials and/or activation times in a patient's heart based on a relationship between the heart locations of the torso-surface potentials and torso model, and the torso model to model heart, all used to map corresponding torso-surface potentials to the model heart. The torso model can include typical geometric locations of each of its corresponding plurality of external electrodes. The geometric locations of the plurality of external electrodes of the torso model can be correlated with corresponding geometric locations of a model heart.

From these torso-surface potential signals, a metric of electrical activity can be calculated and also mapped to the corresponding locations of the model heart. A metric of electrical activity can include any one of activation times, gradient of activation time, peak-to-peak QRS voltages, etc. Low amplitude peak-to-peak QRS voltages can be indicative of scarring of heart tissue. The metrics of electrical activity can include metrics of electrical heterogeneity. The metrics of electrical heterogeneity can include a metric of standard deviation of activation times (SDAT) of electrodes on a left side of a torso of the patient and/or a metric of mean left ventricular activation time (LVAT) of electrodes on the left side of the torso of the patient. A metric of LVAT may be determined from electrodes on both the anterior and posterior surfaces. The metrics of electrical heterogeneity information can include a metric of mean right ventricular activation time (RVAT) of electrodes on the right side of the torso of the patient. A metric of RVAT may be determined from electrodes on both the anterior and posterior surfaces. The metrics of electrical heterogeneity can include a metric of mean total activation time (mTAT) taken from a plurality of electrode signals from both sides of the torso of the patient, or it may include other metrics (e.g., standard deviation, interquartile deviations, a difference between a latest activation time and earliest activation time) reflecting a range or dispersion of activation times on a plurality of electrodes located on the right side of the patient torso or left side of the patient torso, or combining both right and left sides of the patient torso.

The block diagram of <FIG> is an exemplary method <NUM> of mapping, or regionalizing, electrical activity on a model heart. The method <NUM> can include monitoring electrical activity using a plurality of external electrodes <NUM> such as the electrodes <NUM> of the electrode apparatus <NUM> described herein with reference to <FIG>. The monitored electrical activity can include torso-surface potential signals monitored at a plurality of locations associated with each of the plurality of external electrodes. The monitored electrical activity can be used to determine, or generate, cardiac activation times and/or peak-to-peak QRS voltages. As used herein, peak-to-peak voltage can refer to a difference between a maximum and minimum voltage of each location on a model during the QRS wave that coincides with and is generated by the depolarization of the heart. As an example, for a typical unipolar electrogram the maximum voltage can occur at a top of an upward deflection of an R-wave within a QRS complex, a minimum voltage can occur at the bottom of a downward deflection of an S-wave of a QRS complex, and the difference in amplitudes between the maximum and minimum represents the peak-to-peak voltage.

The method <NUM> can further include providing a model heart <NUM>. The model heart may be a two-dimensional or three-dimensional representation of the patient's heart and may include a plurality of segments. In one or more embodiments, the plurality of segments may be defined as surface portions of the model heart. Further, in one or more embodiments, each segment may be separate from each other. Further, it may be described that each of the plurality of segments may be a polygon such as, for example, a triangle. The model heart may be described as being defined by, or made up of, a plurality of vertices for representation or approximating the exterior surface of the heart. Three of the vertices may be connected via lines, or edges, to define a planar triangular surface (e.g., a polygon). A plurality of planar triangular surfaces may be used to form the complex shape of the heart. In other words, the model heart may be described as being a model heart using polygonal modeling using a plurality of vertices linked to provide a plurality of edges (e.g., lines between verifies) and plurality of polygons (e.g., triangles, quads, etc.), which may form a plurality of non-self-intersecting meshes. In one embodiment, each segment may correspond to one of the plurality of polygons. For example, each triangle formed by three vertices (or polygon formed by more than three vertices) may be, or define, a segment. In another embodiment, each segment may correspond to more than one of the plurality of polygons. For example, two or more triangles, each formed by three vertices, (or polygons, each formed by more than three vertices) may be, or define, a segment. In this way, the resolution of the anatomic regions may be the same as or less than the polygonal modelling of the model heart. In at least one example, the segments can be defined by existing clinical standards (e.g., according to an American Heart Association (AHA) model).

The method <NUM> can further include mapping the monitored electrical activity onto the plurality of segments of the model heart <NUM>. More details regarding at least one embodiment for mapping, or projecting, the monitored electrical activity onto the plurality of segments of the model heart <NUM> are described further herein with respect to <FIG>. In one example, the model heart can be provided with segments already defined, or divided, and the monitored electrical activity can be projected on the segments based on the locations (of the torso surface of the patient) of the electrodes from which the electrical activity was monitored. In another example, the model heart can be provided without the segments defined or "divided out. " When the model heart is provided without defined segments, the model heart can be segmented before or after mapping electrical activity onto the model heart. That is, the model heart can be provided, divided into segments and then the electrical activity can be mapped onto those segments.

The method <NUM> can further include determining a value of electrical activity for each of a plurality of anatomic regions of the model heart based on the mapped electrical activity <NUM>. The plurality of anatomic regions of the model heart can each include a plurality of segments. That is, a first anatomic region can include a first plurality of segments of the model heart and a second anatomic region can include a second plurality of segments of the model heart. In determining the value of electrical activity for an anatomic region, the value can incorporate values from electrical activity from each of the segments within that anatomic region. As an example, each of the first plurality of segments of the model heart in the first anatomic region can have electrical activity that includes activation times. The activations times of the first plurality of segments can be averaged, or combined in some fashion (e.g., median, maximum, average, etc.), and the first anatomic region can be associated with the averaged activation times for that region.

A detailed block diagram of providing a model heart <NUM> is depicted in <FIG>. The method <NUM> of <FIG> can be described as one exemplary embodiment of method step <NUM> in method <NUM> described in association with <FIG>. That is, providing a model heart <NUM> of method <NUM> can include the steps of method <NUM> in <FIG>. Generally, it may be described that providing a model heart <NUM> may include one or both of selecting a model heart from a plurality of model hearts based on one or more patient characteristics and generating a model heart based on one or more patient characteristics.

The method <NUM> may include providing one or more patient characteristics <NUM>. The one or more patient characteristics may be used to select, generate, and modify the model heart for the patient. In other words, the model heart may be "picked" or "created" based on the one or more characteristics of the patient such that the model heart ultimately provided by method <NUM> approximates the patient's heart without requiring time-consuming and potentially expensive imaging procedures to obtain a model of the patient's heart. The characteristic of the patient can include at least one of age, gender, height, weight, chest circumference, heart chamber dimensions (e.g., end-systolic and end-diastolic diameters of at least one of the left and right ventricles), ventricular ejection fraction, type of cardiomyopathy, duration of QRS complex on <NUM>-lead ECG, among other characteristics. Further, it is understood that the exemplary methods and processes descried herein may be configured to use one or a plurality of the patient characteristics to select, generate, and/or modify a model heart for the patient.

The patient characteristics can then be used to provide a model heart. For example, the method <NUM> may further include providing a plurality of model hearts <NUM>. As described above, the plurality of model hearts can be provided from a library and/or catalogue of model hearts that have already been generated, for example, based on one or more various patients (different from that who is presently being evaluated) and/or based on one or more known cardiac models approximating the size, shape, and structure of a human heart. Each model heart of the plurality of model hearts may be correlated to, or correspond with, patient characteristics from which the model hearts where derived or generated from. For example, if each model heart were acquired from imaging of a patient (different from that who is presently being evaluated), each model heart may be associated with the plurality of patient characteristics of the such patient. Further, if each model heart were acquired from imaging of a plurality of patients, each model heart may be associated with the plurality of patient characteristics that may be compiled from the plurality of patients. In other words, each of the model hearts may come with, or be associated with, a plurality of patient characteristics that were generated, or derived, from the patients whose hearts were modelled for the model hearts.

Further, the plurality of model hearts of the library can be described as being already generated, or pre-generated, such that, for example, patients do not need to be imaged or are being scanned using computed tomography (CT), magnetic resonance imaging (MRI), etc. In this way, the exemplary systems and methods described herein may be less cumbersome and more cost effective.

The method <NUM> may further include selecting a model heart from the plurality of model hearts <NUM> based on the provided one or more patient characteristics without the use of imaging or scanning (MRI, CT, etc.) of the patient's heart. In other words, the provided patient characteristics of the present patient may be attempted to be approximately "matched" with the patient characteristics of a corresponding model heart. In this way, the selected model heart, although not generated from imaging of the present patient, may be described as being representative of the present patient's heart. For example, the model heart may be selected based on age, gender, and chest circumference, and thus, the model heart of the library and/or catalogue of model hearts that best corresponds to, or correlates with, the patient's age, gender, and chest circumference may be selected. Further, for example, the model heart may be selected based on height, age, and ventricular ejection, and thus, the model heart of the library and/or catalogue of model hearts that best corresponds to, or correlates with, the patient's height, age, weight, chest circumference and heart dimensions (e.g., left ventricular end-systolic and end-diastolic diameters), and thus, the model heart of the library and/or catalogue of model hearts that best corresponds to, or correlates with, the patients height, age, and dimensions may be selected.

Further, the method <NUM> may further include, in conjunction or alternative to the processes <NUM>, <NUM>, generating a model heart <NUM> based on one or more patient characteristics without the use of imaging or scanning (MRI, CT, etc.) of the patient's heart. For example, the patient characteristics may be input in a model heart generation process (e.g., three-dimensional model heart generation process) that may then generate the model heart based on such patient characteristics. The model heart generation process may utilize known sizes, shapes, and locations of portions, regions, and structures of the human heart correlated to the patient characteristics, and then the model heart may be generated using the inputted patient characteristics. For example, the size of a patient's heart may be approximated based on a width and/or length of the patient's heart and/or torso, ejection fraction, heart dimensions (e.g., left ventricular end-systolic and/or end-diastolic diameters), coronary anatomy from venogram, and chest circumference. Thus, the model heart generation process may include calculations, or algorithms, that determine the size of the model heart based on the width and/or length of the patient's heart and/or torso, input ejection fraction, heart dimensions, and chest circumference of the patient.

Further, the method <NUM> may include modifying a selected model heart using the inputted, or provided, patient characteristics <NUM>. For example, the model heart can be provided by using a model heart from the plurality of model hearts <NUM> as a guide and modifying the model heart to be more in line with the characteristic of the patient using the modifying process <NUM>. As an example, a model heart of the plurality of model hearts may be from a previous patient whose characteristics may be relatively closes to the patient's characteristics but in order to get a more accurate model heart, the model heart may be modified to compensate for any differences between the characteristics of the previous patient and the patient. In other words, the selected model heart can be modified in line with the differences in characteristics of the patients. If the model heart selected is derived from a previous patient that has a characteristic that is difference that that of the present patient, such as chest circumference, then selected model heart can be modified to account for the difference (e.g., a smaller or larger chest circumference). In this way, a combination of a library of model hearts and a modification of the selected model heart for the current patient can be used.

<FIG> is a detailed block diagram of mapping electrical activity onto a plurality of anatomic regions of the model heart <NUM>. The method <NUM> of <FIG> can be described as one exemplary embodiment of method step <NUM> in method <NUM> described in association with <FIG>. That is, mapping electrical activity onto a plurality of anatomic regions of the model heart <NUM> of method <NUM> can include the steps of method <NUM> in <FIG>. The method <NUM> can include projecting locations at which torso-surface potential signals are monitored onto corresponding locations on a model torso <NUM>. The model torso can be associated with a provided and/or selected model heart. That is, the model torso of the previous patient who is associated with the model heart can be used to project the locations of the torso-surface potential signals onto.

The method <NUM> of <FIG> can further include projecting the torso-surface potential signals onto segments on the model heart <NUM>. The torso-surface potential signals can be projected onto segments on the model heart based on a geometric relationship between the model heart and the model torso. As an example, the torso of the patient is correlated with locations of segments on the model torso and the model torso has a geometric relationship to the segment locations on the model heart. In this way, the locations of the torso-surface potential signals can be correlated to segment locations on the model heart.

The method <NUM> of <FIG> can further include generating a value for each anatomic region based on the corresponding torso-surface potential signals of the segments <NUM>. Generating the value for each anatomic region can include combining values from each of a plurality of segments within each anatomic region. For example, the generated value can include at least one of an activation time and/or a peak-to-peak voltage associated with the torso-surface potential signals that were projected onto the plurality of segments within each anatomic region. In at least one example, the generated value can include averaging activation times of these plurality of segments that are within and/or within a threshold proximity to the anatomic region. In at least one example, the generated value can include averaging peak-to-peak voltages that are within and/or within a threshold proximity to the anatomic region. The method <NUM> of <FIG> can further include mapping the values onto the anatomic regions <NUM>. The values can be mapped onto the anatomic regions by numerical display, graphical display, color-coordinated or grey shading display, etc., that is further described in association with <FIG>.

The method <NUM> of <FIG> can further optionally include determining an indication of scar risk <NUM>. In at least one example, a determination of scar risk can be based on peak-to-peak values that are below a particular threshold. In at least one example, an anatomic region can be determined to include a scar risk in response to the anatomic region including an averaged peak-to-peak value that is below a threshold value. The anatomic region with the scar risk can be tagged with an indicator that indicates the anatomic region has a higher risk of scar. Implanters of a lead or leadless pacer may want to target areas of late electrical activation without this scar risk indicator as a preliminary implant target region.

The block diagram of <FIG> is an exemplary method <NUM> of determining and mapping conductive conditions such as slow conduction activity, a conduction block, etc.. More specifically, the method <NUM> can include comparing monitored electrical activity mapped to adjacent anatomic regions <NUM>, and then determining conduction conditions based on compared adjacent anatomic regions <NUM>. As an example, a first anatomic region can be adjacent to a second anatomic region. The electrical activity of the first anatomic region can be compared to the electrical activity of the second anatomic region. The electrical activity compared can include activation times, peak-to-peak voltage values, etc..

In other words, conduction conditions can be determined in response to a high gradient between the electrical activity of adjacent first and second anatomic regions. Adjacent anatomic regions with a high gradient of difference in electrical activity illustrates that the conduction is having difficulty passing from one anatomic region to the next adjacent anatomic region. For example, a percentage difference may be calculated between the values (e.g., peak-to-peak values) of mapped anatomic regions, and if the percentage difference exceeds a selected threshold indication of a conduction condition (e.g., such as a block), it may be determined that a conduction condition exists between such anatomic regions.

The method <NUM> may further include display of the conduction conditions <NUM> such as shown in <FIG>. For example, a graphical element (e.g., a line) indicative of a location of the determined slow conduction or conduction block conditions may be depicted, or displayed, on the model heart, e.g., between adjacent anatomic regions that were determined to have a conduction condition. In response to electrical heterogeneity during pacing not being reduced by more than a selected threshold at the intersection of these adjacent anatomic regions, an implanter may use information from the electrical activity during pacing to target a lead location (for example, target anatomic regions that circumvent the line of conduction block, etc.).

<FIG> depicts an exemplary model heart <NUM> including a plurality of anatomic regions <NUM> using the exemplary systems and methods described herein with reference to <FIG>. Thus, the exemplary model heart <NUM> including a plurality of anatomic regions <NUM> and electricity activity mapped thereto may have been generated, or created, without imaging the patient's heart, and instead, using one or more patient characteristics to provide the model heart <NUM> and map the electrical activity thereon. As shown, a labelled regions indicator <NUM> may be depicted proximate the model heart <NUM> and may be used to indicate a particular anatomic region of the model heart <NUM>. As is illustrated in <FIG>, anatomic region <NUM>-<NUM> corresponds to the color/shade of the labelled regions indicator <NUM> that indicates "heart valves. " This region of the heart may not have electrically active myocardium, but may be included in this diagram in order to fully capture the geometry of the heart in order for other, electrically active portions of the myocardium to be properly illustrated and its corresponding electrical activity properly mapped and/or projected.

Further, as further described herein with reference to process <NUM>, the model heart <NUM> can be described as a three-dimensional (3D) representation that extends in the x, y, and z planes, indicated by axes <NUM> (x-plane), <NUM> (y-plane), and <NUM> (z-plane) and as including a plurality of anatomic regions, a few of which are labeled as <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> (hereinafter referred to collectively as <NUM>). Each of the anatomic regions <NUM> can include a plurality of segments (e.g., the triangular shapes illustrated) that make up that corresponding anatomic region. Put another way, each of the anatomic regions <NUM> can include a subset of the plurality of segments that cover the entire heart model <NUM>. Each of the anatomic regions <NUM> can be indicated by a corresponding shade/color of the labelled regions indicator <NUM> of the model heart <NUM>. As an example, anatomic region <NUM>-<NUM> can correspond to a shade/color on the labelled regions indicator <NUM> that corresponds to the left ventricular posterior lateral base (LV Post Lat Base). That is, all of the segments in anatomic region <NUM>-<NUM> are of a same shade/color from the labelled regions indicator <NUM>. Further, anatomic region <NUM>-<NUM> can correspond to a shade/color on the labelled regions indicator <NUM> that corresponds to the right ventricular anterior apex (RV Ant Apex). As will be described further in association with <FIG>, the anatomic regions <NUM> can each experience a different level or value of electrical activity. In at least one example, due to artifacts of the mapping, at least one segment (e.g., triangular segment) of a particular region can be non-contiguous with other segments of that particular region. As illustrated in <FIG>, bolded lines can indicate a boundary between two labeled regions. However, in at least one example, the bolded lines may be omitted and are used here only for illustrative purposes.

As illustrated in <FIG>, a model heart <NUM> can include a plurality of segments, a few that border other segments with differing activation times and are labeled as <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> (hereinafter referred to collectively as <NUM>). The segments <NUM> can each experience a different level or value of electrical activity, indicated by a correspondence between the shade/color of the electrical activity indicator <NUM> and those on the model heart <NUM>. The electrical activity can be mapped to the segments <NUM> of the model heart <NUM>. The model heart <NUM> illustrated in <FIG> illustrates segments that have not been combined and/or divided into anatomic regions, as will be further discussed in association with <FIG>.

In this embodiment, the electrical activity mapped about, or onto, the model heart <NUM> within the segments <NUM> are cardiac activation times. As described herein, the cardiac activation times may be described as being representative of the timing of the depolarization of the cardiac tissue. In one or more embodiments, measurement of activation times can be performed by measuring the period of time between an onset of cardiac depolarization (e.g., onset of QRS complex) and an appropriate fiducial point such as, e.g., a peak value, a minimum value, a minimum slope, a maximum slope, a zero crossing, a threshold crossing, etc..

That is, a first segment <NUM>-<NUM> is illustrated as having an electrical activity value, or activation time, corresponding to around twelve (<NUM>) on the indicator <NUM>. A second segment <NUM>-<NUM> is illustrated as having an electrical activity value, or activation time, corresponding to around eighty (<NUM>) on the indicator <NUM>. A third <NUM>-<NUM> and fourth <NUM>-<NUM> segment each have electrical activity value, or activation time, corresponding to eighty (<NUM>) and around twelve (<NUM>), respectively, as well. A fifth segment <NUM>-<NUM> has an electrical activity value, or activation time, corresponding to around seventy (<NUM>) on the electrical activity indicator <NUM>. A sixth segment <NUM>-<NUM> has an electrical activity value, or activation time, corresponding to around fifty (<NUM>) on the electrical activity indictor <NUM>. In this embodiment, each of the mentioned segments can be surrounded by further segments of about the same or very different electrical activity values.

Further, <FIG> depicts an exemplary model heart <NUM> illustrating, or having, a few possible conduction conditions. The first segment <NUM>-<NUM> and the fourth segment <NUM>-<NUM> have a similar electrical activity, as illustrated, and a second segment <NUM>-<NUM> and a third segment <NUM>-<NUM> have similar electrical activity. However, the adjacent first <NUM>-<NUM> and second <NUM>-<NUM> segments include electrical activities that may be described as varying or differing too much. That is, there is a gradient at the boundary <NUM> of the first <NUM>-<NUM> and second <NUM>-<NUM> segments, which may indicate a conduction condition, such as slow conduction condition or a conduction block condition. Further, another example gradient of electrical activities is illustrated at a boundary <NUM> between the third <NUM>-<NUM> and the fourth <NUM>-<NUM> segments, also indicating a conduction condition.

<FIG> depicts an exemplary model heart illustrating a plurality of anatomic regions and cardiac electrical activation times mapped thereto. The model heart <NUM> can include a plurality of anatomic regions <NUM>, where each labeled region or group of regions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> indicates at least one region that a median activation time has been determined. That is, a labeled region, such as <NUM>-<NUM> in <FIG> can include both regions <NUM>-<NUM> and <NUM>-<NUM> illustrated in <FIG> as those two regions <NUM>-<NUM> and <NUM>-<NUM> have a same median activation time (e.g., approximately <NUM>), as illustrated in <FIG>. As illustrated in <FIG>, bolded lines can indicate a boundary between at least two labeled regions. However, in at least one example, the bolded lines may be omitted and are used here only for illustrative purposes.

Each of the anatomic regions <NUM> can include a subset of the plurality of segments across the entire heart model <NUM>, where a segment of the plurality of segments is illustrated by a triangular shape of the model heart <NUM>. The plurality of anatomic regions <NUM> are illustrated with a mapping of the electrical activity of each segment illustrated in <FIG> being combined across each anatomic region in <FIG>. That is, as an example, the electrical activity of segments, illustrated in <FIG>, that correspond to an anatomic region can be averaged for that anatomic region, which is illustrated in <FIG>. Put another way, the electrical activity illustrated in <FIG> is on a segment-by-segment basis and is averaged, illustrated in <FIG>, within an anatomic region in order to be on a region-by-region basis. As described in association with <FIG>, some anatomic regions may be associated with myocardium that are not electrically active (e.g., such as anatomic region <NUM>-<NUM> in <FIG>). In order to compensate for this, these electrically inactive portions of the myocardium of the heart can be assigned an electrical activity value of -<NUM> to indicate that these are not regions of interest, as will be further described in association with <FIG> below.

A regional median activation time indicator <NUM> is illustrated and depicts a color/shade scheme that corresponds with median activation times for each region. That is, anatomic region <NUM>-<NUM> has a median activation time (e.g., the median activation time for all the segments within anatomic region <NUM>-<NUM>) corresponding to around ten (<NUM>) ms (shown in white within <NUM>-<NUM>) on the electrical activity indicator <NUM>. Anatomic region <NUM>-<NUM> is assigned a median activation time of negative one (-<NUM>) ms on the regional median activation time indicator <NUM> which indicates that this anatomical region is not activating myocardium, i.e., not activating valves and vessels. Anatomic region <NUM>-<NUM> has a median activation time corresponding to around ten (<NUM>) ms, anatomic region <NUM>-<NUM> has a median activation time corresponding to around eighty (<NUM>) ms (shown in black within <NUM>-<NUM>), and so forth.

<FIG> depicts the exemplary model heart <NUM> illustrating a few conduction conditions indicated by conduction condition indicators. As described in association with <FIG>, there can be an electrical activity gradient between two adjacent anatomic regions, such as between first <NUM>-<NUM> and second <NUM>-<NUM> anatomic regions. That is, anatomic region <NUM>-<NUM> has a median activation time corresponding to around ten (<NUM>) ms on a regional median activation time indicator <NUM> and anatomic region <NUM>-<NUM>, which is adjacent to anatomic region <NUM>-<NUM>, has a median activation time corresponding to around eighty (<NUM>) ms. The gradient between the adjacent anatomic regions can indicate a conduction condition. The conduction condition can be visually illustrated by a conduction condition indicator such as a graphical element (e.g., line) <NUM> between first <NUM>-<NUM> and second <NUM>-<NUM> anatomic regions. While a graphical element is described, any number of elements can be used to indicate the conduction condition, such as an arrow, a displayed letter, etc..

<FIG> depicts an exemplary model heart illustrating a plurality of anatomic regions and cardiac electrical activation times mapped thereto. The model heart <NUM> can include a plurality of anatomic regions, a few of which are labeled as <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>. The plurality of anatomic regions <NUM> are illustrated with a mapping of the electrical activity of each segment illustrated in <FIG> being combined across each anatomic region in <FIG>. That is, as an example, the electrical activity of segments, illustrated in <FIG>, that correspond to an anatomic region can be used to determine a regional maximum activation time for that anatomic region, which is illustrated in <FIG>. Put another way, the electrical activity illustrated in <FIG> is on a segment-by-segment basis and the maximum of the electrical activity in those segments is illustrated in <FIG> for each anatomic region in order to be on a region-by-region basis.

A regional maximum activation time indicator <NUM> is illustrated and depicts a color/shade scheme that corresponds with the maximum activation times for each region. That is, anatomic region <NUM>-<NUM> has a maximum activation time (e.g., the maximum activation time for all the segments within anatomic region <NUM>-<NUM>) corresponding to around twenty (<NUM>) ms on the electrical activity indicator <NUM>. Anatomic region <NUM>-<NUM> has a maximum activation time corresponding to around negative one (-<NUM>) ms on the regional median activation time indicator <NUM> which indicates that this anatomical region is not activating myocardium, i.e., not activating valves and vessels. Further, anatomic region <NUM>-<NUM> has a maximum activation time corresponding to around eighty (<NUM>) ms, anatomic region <NUM>-<NUM> has a maximum activation time corresponding to around eighty (<NUM>) ms, and so forth.

<FIG> depicts an exemplary model heart <NUM> including a plurality of anatomic regions <NUM> and peak-to-peak voltage values mapped thereto using the exemplary systems and methods described herein with reference to <FIG>. Thus, the exemplary model heart <NUM> including a plurality of segments <NUM> and peak-to-peak voltage values mapped thereto may have been generated, or created, without imaging the patient's heart, and instead, using one or more patient characteristics to provide the model heart <NUM> and map the peak-to-peak voltage values thereon. The segments <NUM> can each experience a different level or value of peak-to-peak voltage, indicated by a correspondence between the shade/color of the peak-to-peak voltage indicator <NUM> and those on the model heart <NUM>.

Further, as further described herein with reference to process <NUM>, the model heart <NUM> can be described as a three-dimensional (3D) representation that extends in the x, y, and z planes, indicated by axes <NUM> (x-plane), <NUM> (y-plane), and <NUM> (z-plane) and as including a plurality of segments, a few of which are labeled as <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> (referred to herein collectively as <NUM>).

A first segment <NUM>-<NUM> is illustrated as having a peak-to-peak voltage value corresponding to around twelve (<NUM>) millivolts (mV) on the indicator <NUM>. A second segment <NUM>-<NUM> is illustrated as having a peak-to-peak voltage value corresponding to around nine (<NUM>) mV on the indicator <NUM>. A third <NUM>-<NUM> segment has a peak-to-peak voltage value corresponding to five (<NUM>) mV, a fourth <NUM>-<NUM> corresponding to two (<NUM>) mV, and a fifth <NUM>-<NUM> corresponding to three (<NUM>) mV. In this embodiment, each of the mentioned segments can be surrounded by further segments of about the same or very different peak-to-peak voltage values.

While not illustrated in <FIG>, the peak-to-peak voltages can be averaged and/or combined across an anatomic region, as described in association with <FIG>. In this example, the peak-to-peak voltage values can be an average of peak-to-peak voltages across the anatomic region and not necessarily a particular location within the anatomic region with that value. When traversing away from the mentioned anatomic regions, boundaries extend between anatomic regions of differing peak-to-peak voltages (as described above in association with <FIG> and electrical activation times).

<FIG> depicts an exemplary model heart illustrating peak-to-peak voltage values. The model heart <NUM> illustrates a plurality of peak-to-peak voltage values indicated by the peak-to-peak indicator <NUM>. The peak-to-peak voltage values of the model heart <NUM> are between <NUM> mV and <NUM> mV on the peak-to-peak indicator <NUM>, approximately near <NUM> mV. This peak-to-peak voltage value at approximately <NUM> mV is above a threshold that indicates that there is an absence of scar risk in the model heart tissue.

<FIG> depicts an exemplary model heart illustrating peak-to-peak voltage values including scar risk indicators identifying increased scar risk. The model heart <NUM> illustrates a plurality of peak-to-peak voltage values indicated by the peak-to-peak indicator <NUM>. The peak-to-peak voltage values, indicated by arrows <NUM>, of the model heart <NUM> are between <NUM> mV and <NUM> mV on the peak-to-peak indicator <NUM>, approximately near <NUM> mV. This peak-to-peak voltage value at approximately <NUM> mV is above a threshold that indicates that there is an absence of scar risk at these locations in the model heart tissue. However, there are portions <NUM> of the model heart <NUM> that are below a threshold, at about <NUM> mV on the peak-to-peak indicator <NUM>. This does indicate a scar risk in the model heart tissue. In response to a portion of the model heart tissue having a peak-to-peak voltage value below a threshold, a scar risk indicator <NUM> can be displayed on the model heart <NUM>.

The exemplary systems, methods, and graphical user interfaces described herein may be used with respect to the implantation and configuration of an implantable medical device (IMD) and/or one or more leads configured to be located proximate one or more portions of a patient's heart. For example, the exemplary systems, methods, and interfaces may be used in conjunction with an exemplary therapy system <NUM> described herein with reference to <FIG>.

<FIG> is a conceptual diagram illustrating an exemplary therapy system <NUM> that may be used to deliver pacing therapy to a patient <NUM>. Patient <NUM> may, but not necessarily, be a human. The therapy system <NUM> may include an implantable medical device <NUM> (IMD), which may be coupled to leads <NUM>, <NUM>, <NUM>. The IMD <NUM> may be, e.g., an implantable pacemaker, cardioverter, and/or defibrillator, that delivers, or provides, electrical signals (e.g., paces, etc.) to and/or senses electrical signals from the heart <NUM> of the patient <NUM> via electrodes coupled to one or more of the leads <NUM>, <NUM>, <NUM>.

The leads <NUM>, <NUM>, <NUM> extend into the heart <NUM> of the patient <NUM> to sense electrical activity of the heart <NUM> and/or to deliver electrical stimulation to the heart <NUM>. In the example shown in <FIG>, the right ventricular (RV) lead <NUM> extends through one or more veins (not shown), the superior vena cava (not shown), and the right atrium <NUM>, and into the right ventricle <NUM>. The left ventricular (LV) coronary sinus lead <NUM> extends through one or more veins, the vena cava, the right atrium <NUM>, and into the coronary sinus <NUM> to a region adjacent to the free wall of the left ventricle <NUM> of the heart <NUM>. The right atrial (RA) lead <NUM> extends through one or more veins and the vena cava, and into the right atrium <NUM> of the heart <NUM>.

The IMD <NUM> may sense, among other things, electrical signals attendant to the depolarization and repolarization of the heart <NUM> via electrodes coupled to at least one of the leads <NUM>, <NUM>, <NUM>. In some examples, the IMD <NUM> provides pacing therapy (e.g., pacing pulses) to the heart <NUM> based on the electrical signals sensed within the heart <NUM>. The IMD <NUM> may be operable to adjust one or more parameters associated with the pacing therapy such as, e.g., AV delay and other various timings, pulse wide, amplitude, voltage, burst length, etc. Further, the IMD <NUM> may be operable to use various electrode configurations to deliver pacing therapy, which may be unipolar, bipolar, quadripolar, or further multipolar. For example, a multipolar lead may include several electrodes that can be used for delivering pacing therapy. Hence, a multipolar lead system may provide, or offer, multiple electrical vectors to pace from.

A pacing vector may include at least one cathode, which may be at least one electrode located on at least one lead, and at least one anode, which may be at least one electrode located on at least one lead (e.g., the same lead, or a different lead) and/or on the casing, or can, of the IMD. While improvement in cardiac function as a result of the pacing therapy may primarily depend on the cathode, the electrical parameters like impedance, pacing threshold voltage, current drain, longevity, etc. may be more dependent on the pacing vector, which includes both the cathode and the anode. The IMD <NUM> may also provide defibrillation therapy and/or cardioversion therapy via electrodes located on at least one of the leads <NUM>, <NUM>, <NUM>. Further, the IMD <NUM> may detect arrhythmia of the heart <NUM>, such as fibrillation of the ventricles <NUM>, <NUM>, and deliver defibrillation therapy to the heart <NUM> in the form of electrical pulses. In some examples, IMD <NUM> may be programmed to deliver a progression of therapies, e.g., pulses with increasing energy levels, until a fibrillation of heart <NUM> is stopped.

<FIG> are conceptual diagrams illustrating the IMD <NUM> and the leads <NUM>, <NUM>, <NUM> of therapy system <NUM> of <FIG> in more detail. The leads <NUM>, <NUM>, <NUM> may be electrically coupled to a therapy delivery module (e.g., for delivery of pacing therapy), a sensing module (e.g., for sensing one or more signals from one or more electrodes), and/or any other modules of the IMD <NUM> via a connector block <NUM>. In some examples, the proximal ends of the leads <NUM>, <NUM>, <NUM> may include electrical contacts that electrically couple to respective electrical contacts within the connector block <NUM> of the IMD <NUM>. In addition, in some examples, the leads <NUM>, <NUM>, <NUM> may be mechanically coupled to the connector block <NUM> with the aid of set screws, connection pins, or another suitable mechanical coupling mechanism.

Each of the leads <NUM>, <NUM>, <NUM> includes an elongated insulative lead body, which may carry a number of conductors (e.g., concentric coiled conductors, straight conductors, etc.) separated from one another by insulation (e.g., tubular insulative sheaths). In the illustrated example, bipolar electrodes <NUM>, <NUM> are located proximate to a distal end of the lead <NUM>. In addition, bipolar electrodes <NUM>, <NUM>, <NUM>, <NUM> are located proximate to a distal end of the lead <NUM> and bipolar electrodes <NUM>, <NUM> are located proximate to a distal end of the lead <NUM>.

The electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may take the form of ring electrodes, and the electrodes <NUM>, <NUM> may take the form of extendable helix tip electrodes mounted retractably within the insulative electrode heads <NUM>, <NUM>, <NUM>, respectively. Each of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be electrically coupled to a respective one of the conductors (e.g., coiled and/or straight) within the lead body of its associated lead <NUM>, <NUM>, <NUM>, and thereby coupled to a respective one of the electrical contacts on the proximal end of the leads <NUM>, <NUM>, <NUM>.

Additionally, electrodes <NUM>, <NUM>, <NUM> and <NUM> may have an electrode surface area of about <NUM><NUM> to about <NUM><NUM>. Electrodes <NUM>, <NUM>, <NUM>, and <NUM> may also be referred to as LV1, LV2, LV3, and LV4, respectively. The LV electrodes (i.e., left ventricle electrode <NUM> (LV1) <NUM>, left ventricle electrode <NUM> (LV2) <NUM>, left ventricle electrode <NUM> (LV3) <NUM>, and left ventricle <NUM> (LV4) <NUM> etc.) on the lead <NUM> can be spaced apart at variable distances. For example, electrode <NUM> may be a distance, e.g., of about <NUM> millimeters (mm), away from electrode <NUM>, electrodes <NUM> and <NUM> may be spaced a distance, e.g. of about <NUM> to about <NUM>, away from each other, and electrodes <NUM> and <NUM> may be spaced a distance of, e.g. <NUM> to about <NUM>, away from each other.

The electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may further be used to sense electrical signals (e.g., morphological waveforms within electrograms (EGM)) attendant to the depolarization and repolarization of the heart <NUM>. The electrical signals are conducted to the IMD <NUM> via the respective leads <NUM>, <NUM>, <NUM>. In some examples, the IMD <NUM> may also deliver pacing pulses via the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to cause depolarization of cardiac tissue of the patient's heart <NUM>. In some examples, as illustrated in <FIG>, the IMD <NUM> includes one or more housing electrodes, such as housing electrode <NUM>, which may be formed integrally with an outer surface of a housing <NUM> (e.g., hermetically-sealed housing) of the IMD <NUM> or otherwise coupled to the housing <NUM>. Any of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be used for unipolar sensing or pacing in combination with the housing electrode <NUM>. It is generally understood by those skilled in the art that other electrodes can also be selected to define, or be used for, pacing and sensing vectors. Further, any of electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, when not being used to deliver pacing therapy, may be used to sense electrical activity during pacing therapy.

As described in further detail with reference to <FIG>, the housing <NUM> may enclose a therapy delivery module that may include a stimulation generator for generating cardiac pacing pulses and defibrillation or cardioversion shocks, as well as a sensing module for monitoring the electrical signals of the patient's heart (e.g., the patient's heart rhythm). The leads <NUM>, <NUM>, <NUM> may also include elongated electrodes <NUM>, <NUM>, <NUM>, respectively, which may take the form of a coil. The IMD <NUM> may deliver defibrillation shocks to the heart <NUM> via any combination of the elongated electrodes <NUM>, <NUM>, <NUM> and the housing electrode <NUM>. The electrodes <NUM>, <NUM>, <NUM>, <NUM> may also be used to deliver cardioversion pulses to the heart <NUM>. Further, the electrodes <NUM>, <NUM>, <NUM> may be fabricated from any suitable electrically conductive material, such as, but not limited to, platinum, platinum alloy, and/or other materials known to be usable in implantable defibrillation electrodes. Since electrodes <NUM>, <NUM>, <NUM> are not generally configured to deliver pacing therapy, any of electrodes <NUM>, <NUM>, <NUM> may be used to sense electrical activity and may be used in combination with any of electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In at least one embodiment, the RV elongated electrode <NUM> may be used to sense electrical activity of a patient's heart during the delivery of pacing therapy (e.g., in combination with the housing electrode <NUM>, or defibrillation electrode-to-housing electrode vector).

The configuration of the exemplary therapy system <NUM> illustrated in <FIG> is merely one example. In other examples, the therapy system may include epicardial leads and/or patch electrodes instead of or in addition to the transvenous leads <NUM>, <NUM>, <NUM> illustrated in <FIG>. Additionally, in other examples, the therapy system <NUM> may be implanted in/around the cardiac space without transvenous leads (e.g., leadless/wireless pacing systems) or with leads implanted (e.g., implanted transvenously or using approaches) into the left chambers of the heart (in addition to or replacing the transvenous leads placed into the right chambers of the heart as illustrated in <FIG>). Further, in one or more embodiments, the IMD <NUM> need not be implanted within the patient <NUM>. For example, the IMD <NUM> may deliver various cardiac therapies to the heart <NUM> via percutaneous leads that extend through the skin of the patient <NUM> to a variety of positions within or outside of the heart <NUM>. In one or more embodiments, the system <NUM> may utilize wireless pacing (e.g., using energy transmission to the intracardiac pacing component(s) via ultrasound, inductive coupling, RF, etc.) and sensing cardiac activation using electrodes on the can/housing and/or on subcutaneous leads.

In other examples of therapy systems that provide electrical stimulation therapy to the heart <NUM>, such therapy systems may include any suitable number of leads coupled to the IMD <NUM>, and each of the leads may extend to any location within or proximate to the heart <NUM>. For example, other examples of therapy systems may include three transvenous leads located as illustrated in <FIG>. Still further, other therapy systems may include a single lead that extends from the IMD <NUM> into the right atrium <NUM> or the right ventricle <NUM>, or two leads that extend into a respective one of the right atrium <NUM> and the right ventricle <NUM>.

<FIG> is a functional block diagram of one exemplary configuration of the IMD <NUM>. As shown, the IMD <NUM> may include a control module <NUM>, a therapy delivery module <NUM> (e.g., which may include a stimulation generator), a sensing module <NUM>, and a power source <NUM>.

The control module <NUM> may include a processor <NUM>, memory <NUM>, and a telemetry module <NUM>. The memory <NUM> may include computer-readable instructions that, when executed, e.g., by the processor <NUM>, cause the IMD <NUM> and/or the control module <NUM> to perform various functions attributed to the IMD <NUM> and/or the control module <NUM> described herein. Further, the memory <NUM> may include any volatile, non-volatile, magnetic, optical, and/or electrical media, such as a random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, and/or any other digital media. An exemplary capture management module may be the left ventricular capture management (LVCM) module described in <CIT>.

The processor <NUM> of the control module <NUM> may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and/or equivalent discrete or integrated logic circuitry. In some examples, the processor <NUM> may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, and/or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to the processor <NUM> herein may be embodied as software, firmware, hardware, or any combination thereof.

The control module <NUM> may control the therapy delivery module <NUM> to deliver therapy (e.g., electrical stimulation therapy such as pacing) to the heart <NUM> according to a selected one or more therapy programs, which may be stored in the memory <NUM>. More, specifically, the control module <NUM> (e.g., the processor <NUM>) may control various parameters of the electrical stimulus delivered by the therapy delivery module <NUM> such as, e.g., AV delays, VV delays, pacing pulses with the amplitudes, pulse widths, frequency, or electrode polarities, etc., which may be specified by one or more selected therapy programs (e.g., AV and/or VV delay adjustment programs, pacing therapy programs, pacing recovery programs, capture management programs, etc.). As shown, the therapy delivery module <NUM> is electrically coupled to electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, e.g., via conductors of the respective lead <NUM>, <NUM>, <NUM>, or, in the case of housing electrode <NUM>, via an electrical conductor disposed within housing <NUM> of IMD <NUM>. Therapy delivery module <NUM> may be configured to generate and deliver electrical stimulation therapy such as pacing therapy to the heart <NUM> using one or more of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

For example, therapy delivery module <NUM> may deliver pacing stimulus (e.g., pacing pulses) via ring electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> coupled to leads <NUM>, <NUM>, <NUM> and/or helical tip electrodes <NUM>, <NUM> of leads <NUM>, <NUM>. Further, for example, therapy delivery module <NUM> may deliver defibrillation shocks to heart <NUM> via at least two of electrodes <NUM>, <NUM>, <NUM>, <NUM>. In some examples, therapy delivery module <NUM> may be configured to deliver pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, therapy delivery module <NUM> may be configured deliver one or more of these types of stimulation in the form of other signals, such as sine waves, square waves, and/or other substantially continuous time signals.

The IMD <NUM> may further include a switch module <NUM> and the control module <NUM> (e.g., the processor <NUM>) may use the switch module <NUM> to select, e.g., via a data/address bus, which of the available electrodes are used to deliver therapy such as pacing pulses for pacing therapy, or which of the available electrodes are used for sensing. The switch module <NUM> may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple the sensing module <NUM> and/or the therapy delivery module <NUM> to one or more selected electrodes. More specifically, the therapy delivery module <NUM> may include a plurality of pacing output circuits. Each pacing output circuit of the plurality of pacing output circuits may be selectively coupled, e.g., using the switch module <NUM>, to one or more of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (e.g., a pair of electrodes for delivery of therapy to a bipolar or multipolar pacing vector). In other words, each electrode can be selectively coupled to one of the pacing output circuits of the therapy delivery module using the switching module <NUM>.

The sensing module <NUM> is coupled (e.g., electrically coupled) to sensing apparatus, which may include, among additional sensing apparatus, the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to monitor electrical activity of the heart <NUM>, e.g., electrocardiogram (ECG)/electrogram (EGM) signals, etc. The ECG/EGM signals may be used to measure or monitor activation times (e.g., ventricular activations times, etc.), heart rate (HR), heart rate variability (HRV), heart rate turbulence (HRT), deceleration/acceleration capacity, deceleration sequence incidence, T-wave alternans (TWA), P-wave to P-wave intervals (also referred to as the P-P intervals or A-A intervals), R-wave to R-wave intervals (also referred to as the R-R intervals or V-V intervals), P-wave to QRS complex intervals (also referred to as the P-R intervals, A-V intervals, or P-Q intervals), QRS-complex morphology, ST segment (i.e., the segment that connects the QRS complex and the T-wave), T-wave changes, QT intervals, electrical vectors, etc..

The switch module <NUM> may also be used with the sensing module <NUM> to select which of the available electrodes are used, or enabled, to, e.g., sense electrical activity of the patient's heart (e.g., one or more electrical vectors of the patient's heart using any combination of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>). Likewise, the switch module <NUM> may also be used with the sensing module <NUM> to select which of the available electrodes are not to be used (e.g., disabled) to, e.g., sense electrical activity of the patient's heart (e.g., one or more electrical vectors of the patient's heart using any combination of the electrodes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), etc. In some examples, the control module <NUM> may select the electrodes that function as sensing electrodes via the switch module within the sensing module <NUM>, e.g., by providing signals via a data/address bus.

In some examples, sensing module <NUM> includes a channel that includes an amplifier with a relatively wider pass band than the R-wave or P-wave amplifiers. Signals from the selected sensing electrodes may be provided to a multiplexer, and thereafter converted to multi-bit digital signals by an analog-to-digital converter for storage in memory <NUM>, e.g., as an electrogram (EGM). In some examples, the storage of such EGMs in memory <NUM> may be under the control of a direct memory access circuit.

In some examples, the control module <NUM> may operate as an interrupt driven device, and may be responsive to interrupts from pacer timing and control module, where the interrupts may correspond to the occurrences of sensed P-waves and R-waves and the generation of cardiac pacing pulses. Any necessary mathematical calculations may be performed by the processor <NUM> and any updating of the values or intervals controlled by the pacer timing and control module may take place following such interrupts. A portion of memory <NUM> may be configured as a plurality of recirculating buffers, capable of holding one or more series of measured intervals, which may be analyzed by, e.g., the processor <NUM> in response to the occurrence of a pace or sense interrupt to determine whether the patient's heart <NUM> is presently exhibiting atrial or ventricular tachyarrhythmia.

The telemetry module <NUM> of the control module <NUM> may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as a programmer. For example, under the control of the processor <NUM>, the telemetry module <NUM> may receive downlink telemetry from and send uplink telemetry to a programmer with the aid of an antenna, which may be internal and/or external. The processor <NUM> may provide the data to be uplinked to a programmer and the control signals for the telemetry circuit within the telemetry module <NUM>, e.g., via an address/data bus. In some examples, the telemetry module <NUM> may provide received data to the processor <NUM> via a multiplexer.

The various components of the IMD <NUM> are further coupled to a power source <NUM>, which may include a rechargeable or non-rechargeable battery. A non-rechargeable battery may be selected to last for several years, while a rechargeable battery may be inductively charged from an external device, e.g., on a daily or weekly basis.

<FIG> is another embodiment of a functional block diagram for IMD <NUM>. <FIG> depicts bipolar RA lead <NUM>, bipolar RV lead <NUM>, and bipolar LV CS lead <NUM> without the LA CS pace/sense electrodes and coupled with an implantable pulse generator (IPG) circuit <NUM> having programmable modes and parameters of a bi-ventricular DDD/R type known in the pacing art. In tum, the sensor signal processing circuit <NUM> indirectly couples to the timing circuit <NUM> and via data and control bus to microcomputer circuitry <NUM>. The IPG circuit <NUM> is illustrated in a functional block diagram divided generally into a microcomputer circuit <NUM> and a pacing circuit <NUM>. The pacing circuit <NUM> includes the digital controller/timer circuit <NUM>, the output amplifiers circuit <NUM>, the sense amplifiers circuit <NUM>, the RF telemetry transceiver <NUM>, the activity sensor circuit <NUM> as well as a number of other circuits and components described below.

Crystal oscillator circuit <NUM> provides the basic timing clock for the pacing circuit <NUM> while battery <NUM> provides power. Power-on-reset circuit <NUM> responds to initial connection of the circuit to the battery for defining an initial operating condition and similarly, resets the operative state of the device in response to detection of a low battery condition. Reference mode circuit <NUM> generates stable voltage reference and currents for the analog circuits within the pacing circuit <NUM>. Analog-to-digital converter (ADC) and multiplexer circuit <NUM> digitize analog signals and voltage to provide, e.g., real time telemetry of cardiac signals from sense amplifiers <NUM> for uplink transmission via RF transmitter and receiver circuit <NUM>. Voltage reference and bias circuit <NUM>, ADC and multiplexer <NUM>, power-on-reset circuit <NUM>, and crystal oscillator circuit <NUM> may correspond to any of those used in exemplary implantable cardiac pacemakers.

If the IPG is programmed to a rate responsive mode, the signals output by one or more physiologic sensors are employed as a rate control parameter (RCP) to derive a physiologic escape interval. For example, the escape interval is adjusted proportionally to the patient's activity level developed in the patient activity sensor (PAS) circuit <NUM> in the depicted, exemplary IPG circuit <NUM>. The patient activity sensor <NUM> is coupled to the IPG housing and may take the form of a piezoelectric crystal transducer. The output signal of the patient activity sensor <NUM> may be processed and used as a RCP. Sensor <NUM> generates electrical signals in response to sensed physical activity that are processed by activity circuit <NUM> and provided to digital controller/timer circuit <NUM>. Activity circuit <NUM> and associated sensor <NUM> may correspond to the circuitry disclosed in <CIT> and <CIT>. Similarly, the exemplary systems, apparatus, and methods described herein may be practiced in conjunction with alternate types of sensors such as oxygenation sensors, pressure sensors, pH sensors, and respiration sensors, for use in providing rate responsive pacing capabilities. Alternately, QT time may be used as a rate indicating parameter, in which case no extra sensor is required. Similarly, the exemplary embodiments described herein may also be practiced in non-rate responsive pacemakers.

Data transmission to and from the external programmer is accomplished by way of the telemetry antenna <NUM> and an associated RF transceiver <NUM>, which serves both to demodulate received downlink telemetry and to transmit uplink telemetry. Uplink telemetry capabilities may include the ability to transmit stored digital information, e.g., operating modes and parameters, EGM histograms, and other events, as well as real time EGMs of atrial and/or ventricular electrical activity and marker channel pulses indicating the occurrence of sensed and paced depolarizations in the atrium and ventricle.

Microcomputer <NUM> contains a microprocessor <NUM> and associated system clock and on-processor RAM and ROM chips 82A and 82B, respectively. In addition, microcomputer circuit <NUM> includes a separate RAM/ROM chip 82C to provide additional memory capacity. Microprocessor <NUM> normally operates in a reduced power consumption mode and is interrupt driven. Microprocessor <NUM> is awakened in response to defined interrupt events, which may include A-TRIG, RV-TRIG, LV-TRIG signals generated by timers in digital timer/controller circuit <NUM> and A-EVENT, RV-EVENT, and LV-EVENT signals generated by sense amplifiers circuit <NUM>, among others. The specific values of the intervals and delays timed out by digital controller/timer circuit <NUM> are controlled by the microcomputer circuit <NUM> by way of data and control bus from programmed-in parameter values and operating modes. In addition, if programmed to operate as a rate responsive pacemaker, a timed interrupt, e.g., every cycle or every two seconds, may be provided in order to allow the microprocessor to analyze the activity sensor data and update the basic A-A, V-A, or V-V escape interval, as applicable. In addition, the microprocessor <NUM> may also serve to define variable, operative AV delay intervals, V-V delay intervals, and the energy delivered to each ventricle and/or atrium.

In one embodiment, microprocessor <NUM> is a custom microprocessor adapted to fetch and execute instructions stored in RAM/ROM unit <NUM> in a conventional manner. It is contemplated, however, that other implementations may be suitable to practice the present invention. For example, an off-the-shelf, commercially available microprocessor or microcontroller, or custom application-specific, hardwired logic, or state-machine type circuit may perform the functions of microprocessor <NUM>.

Digital controller/timer circuit <NUM> operates under the general control of the microcomputer <NUM> to control timing and other functions within the pacing circuit <NUM> and includes a set of timing and associated logic circuits of which certain ones pertinent to the present invention are depicted. The depicted timing circuits include URI/LRI timers 83A, V-V delay timer 83B, intrinsic interval timers 83C for timing elapsed V-EVENT to V-EVENT intervals or V-EVENT to A-EVENT intervals or the V-V conduction interval, escape interval timers 83D for timing A-A, V-A, and/or V-V pacing escape intervals, an AV delay interval timer 83E for timing the A-LVp delay (or A-RVp delay) from a preceding A-EVENT or A-TRIG, a post-ventricular timer 83F for timing post-ventricular time periods, and a date/time clock <NUM>.

The AV delay interval timer 83E is loaded with an appropriate delay interval for one ventricular chamber (e.g., either an A-RVp delay or an A-LVp) to time-out starting from a preceding A-PACE or A-EVENT. The interval timer 83E triggers pacing stimulus delivery, and can be based on one or more prior cardiac cycles (or from a data set empirically derived for a given patient).

The post-event timer 83F times out the post-ventricular time period following an RV-EVENT or LV-EVENT or a RV-TRIG or LV-TRIG and post-atrial time periods following an A-EVENT or A-TRIG. The durations of the post-event time periods may also be selected as programmable parameters stored in the microcomputer <NUM>. The post-ventricular time periods include the PVARP, a post-atrial ventricular blanking period (PAVBP), a ventricular blanking period (VBP), a post-ventricular atrial blanking period (PVARP) and a ventricular refractory period (VRP) although other periods can be suitably defined depending, at least in part, on the operative circuitry employed in the pacing engine. The post-atrial time periods include an atrial refractory period (ARP) during which an A-EVENT is ignored for the purpose of resetting any AV delay, and an atrial blanking period (ABP) during which atrial sensing is disabled. It should be noted that the starting of the post-atrial time periods and the AV delays can be commenced substantially simultaneously with the start or end of each A-EVENT or A-TRIG or, in the latter case, upon the end of the A-PACE which may follow the A-TRIG. Similarly, the starting of the post-ventricular time periods and the V-A escape interval can be commenced substantially simultaneously with the start or end of the V-EVENT or V-TRIG or, in the latter case, upon the end of the V-PACE which may follow the V-TRIG. The microprocessor <NUM> also optionally calculates AV delays, VV delays, post-ventricular time periods, and post-atrial time periods that vary with the sensor based escape interval established in response to the RCP(s) and/or with the intrinsic atrial and/or ventricular rate.

The output amplifiers circuit <NUM> contains a RA pace pulse generator (and a LA pace pulse generator if LA pacing is provided), a RV pace pulse generator, a LV pace pulse generator, and/or any other pulse generator configured to provide atrial and ventricular pacing. In order to trigger generation of an RV-PACE or LV-PACE pulse, digital controller/timer circuit <NUM> generates the RV-TRIG signal at the time-out of the A-RVp delay (in the case of RV pre-excitation) or the LV-TRIG at the time-out of the A-LVp delay (in the case of LV pre-excitation) provided by AV delay interval timer 83E (or the V-V delay timer 83B). Similarly, digital controller/timer circuit <NUM> generates an RA-TRIG signal that triggers output of an RA-PACE pulse (or an LA-TRIG signal that triggers output of an LA-PACE pulse, if provided) at the end of the V-A escape interval timed by escape interval timers 83D.

The output amplifiers circuit <NUM> includes switching circuits for coupling selected pace electrode pairs from among the lead conductors and the IND-CAN electrode <NUM> to the RA pace pulse generator (and LA pace pulse generator if provided), RV pace pulse generator and LV pace pulse generator. Pace/sense electrode pair selection and control circuit <NUM> selects lead conductors and associated pace electrode pairs to be coupled with the atrial and ventricular output amplifiers within output amplifiers circuit <NUM> for accomplishing RA, LA, RV and LV pacing.

The sense amplifiers circuit <NUM> contains sense amplifiers for atrial and ventricular pacing and sensing. High impedance P-wave and R-wave sense amplifiers may be used to amplify a voltage difference signal that is generated across the sense electrode pairs by the passage of cardiac depolarization wavefronts. The high impedance sense amplifiers use high gain to amplify the low amplitude signals and rely on pass band filters, time domain filtering and amplitude threshold comparison to discriminate a P-wave or R-wave from background electrical noise. Digital controller/timer circuit <NUM> controls sensitivity settings of the atrial and ventricular sense amplifiers <NUM>.

The sense amplifiers may be uncoupled from the sense electrodes during the blanking periods before, during, and after delivery of a pace pulse to any of the pace electrodes of the pacing system to avoid saturation of the sense amplifiers. The sense amplifiers circuit <NUM> includes blanking circuits for uncoupling the selected pairs of the lead conductors and the IND-CAN electrode <NUM> from the inputs of the RA sense amplifier (and LA sense amplifier if provided), RV sense amplifier and LV sense amplifier during the ABP, PVABP and VBP. The sense amplifiers circuit <NUM> also includes switching circuits for coupling selected sense electrode lead conductors and the IND-CAN electrode <NUM> to the RA sense amplifier (and LA sense amplifier if provided), RV sense amplifier and LV sense amplifier. Again, sense electrode selection and control circuit <NUM> selects conductors and associated sense electrode pairs to be coupled with the atrial and ventricular sense amplifiers within the output amplifiers circuit <NUM> and sense amplifiers circuit <NUM> for accomplishing RA, LA, RV, and LV sensing along desired unipolar and bipolar sensing vectors.

Right atrial depolarizations or P-waves in the RA-SENSE signal that are sensed by the RA sense amplifier result in a RA-EVENT signal that is communicated to the digital controller/timer circuit <NUM>. Similarly, left atrial depolarizations or P-waves in the LA-SENSE signal that are sensed by the LA sense amplifier, if provided, result in a LA-EVENT signal that is communicated to the digital controller/timer circuit <NUM>. Ventricular depolarizations or R-waves in the RV-SENSE signal are sensed by a ventricular sense amplifier result in an RV-EVENT signal that is communicated to the digital controller/timer circuit <NUM>. Similarly, ventricular depolarizations or R-waves in the LV-SENSE signal are sensed by a ventricular sense amplifier result in an LV-EVENT signal that is communicated to the digital controller/timer circuit <NUM>. The RV-EVENT, LV-EVENT, and RA-EVENT, LA-SENSE signals may be refractory or non-refractory, and can inadvertently be triggered by electrical noise signals or aberrantly conducted depolarization waves rather than true R-waves or P-waves.

The techniques described in this disclosure, including those attributed to the IMD <NUM>, the computing apparatus <NUM>, and/or various constituent components, may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in programmers, such as physician or patient programmers, stimulators, image processing devices, or other devices. The term "module," "processor," or "processing circuitry" may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.

Such hardware, software, and/or firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules, or components may be implemented together or separately as discrete but interoperable logic devices.

When implemented in software, the functionality ascribed to the systems, devices and techniques described in this disclosure may be embodied as instructions on a computer-readable medium such as RAM, ROM, NVRAM, EEPROM, FLASH memory, magnetic data storage media, optical data storage media, or the like. The instructions may be executed by one or more processors to support one or more aspects of the functionality described in this disclosure.

Claim 1:
A system comprising:
a display (<NUM>), wherein the display comprises a graphical user interface (<NUM>) configured to assist a user in evaluating patient cardiac health;
an electrode apparatus (<NUM>) comprising a plurality of external electrodes (<NUM>) to monitor electrical activity from tissue of a patient; and
a computing apparatus (<NUM>) comprising processing circuitry and coupled to the electrode apparatus and configured to:
monitor electrical activity from the patient using the plurality of external electrodes;
provide a model heart representative of the patient's heart based on at least one of a plurality of patient characteristics, wherein the model heart comprises a plurality of segments;
map the monitored electrical activity onto the plurality of segments of the model heart; and
determine a value of electrical activity for each of a plurality of anatomic regions of the model heart based on the mapped electrical activity, wherein each of the plurality of anatomic regions comprises a subset of the plurality of segments, wherein the computing apparatus is further configured to:
compare values of adjacent anatomic regions of the plurality of anatomic regions; and
determine slow conduction or conduction block conditions between compared adjacent anatomic regions based on the compared values,
wherein the computing apparatus is further configured to display, on the graphical user interface, the model heart and the mapped electrical activity ,
wherein the computing apparatus is further configured to display a graphical element indicative of a location of the determined slow conduction or conduction block conditions on the model heart.