Pacing-induced electrical activation grading

Abstract

To provide a medical procedure system.SOLUTION: In one embodiment, a medical procedure system includes a probe for insertion into a heart chamber of a living subject, and includes: a first electrode to apply a sequence of pacing pulses at a position in the heart chamber; a second electrode to sense an electrical activation signal responsively to electrical activations induced by capture of the pacing pulses in a myocardium of the heart chamber; a display; and processing circuitry. The processing circuitry is configured to: evaluate a successful acquisition by the second electrode of the induced electrical activations responsively to the electrical activation signal, the successful acquisition being indicative of a successful capture of the pacing pulses by the myocardium; compute a capture grade responsively to the evaluation of the successful acquisition of the induced electrical activations, the capture grade being indicative of a count of the induced electrical activations evaluated as being successfully acquired; and render the capture grade to the display.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to medical systems and particularly, but not exclusively, to electrical activation for medical procedures. [Background technology]

[0002] A wide range of medical procedures involve the placement of probes, such as catheters, inside a patient's body. Position sensing systems have been developed to track such probes. Magnetic position sensing is one method known in the art. In magnetic position sensing, magnetic field generators are typically placed at known locations outside the patient's body. A magnetic field sensor in the distal end of the probe generates electrical signals in response to these magnetic fields, and these signals are processed to determine the coordinate position of the distal end of the probe. These methods and systems are described in U.S. Patent Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, WO 1996 / 005768, and U.S. Patent Application Publication Nos. 2002 / 006455, 2003 / 0120150, and 2004 / 0068178. Position may also be tracked using impedance or current-based systems.

[0003] One medical procedure in which these types of probes or catheters have proven extremely useful is in the treatment of cardiac arrhythmias, which, and atrial fibrillation in particular, remain common and dangerous conditions, especially in the aging population.

[0004] Diagnosis and treatment of cardiac arrhythmias involve mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volumes, and selectively ablating cardiac tissue through the application of energy. Such ablation can stop or modify the propagation of unwanted electrical signals from one part of the heart to another. The ablation process disrupts unwanted electrical pathways by creating non-conductive lesions. Various energy delivery modalities have been previously disclosed for creating lesions, including the use of microwave, laser, and more commonly radiofrequency energy to create conduction blocks along cardiac tissue walls. In a two-step mapping-then-ablation procedure, a catheter containing one or more electrical sensors is typically advanced into the heart to sense and measure electrical activity at each point within the heart by acquiring data at multiple points. These data are then used to select a target region of the endocardium for this ablation.

[0005] Electrode catheters have been commonly used in medical practice for many years. They are used to stimulate and map electrical activity within the heart and to ablate sites of abnormal electrical activity. In use, an electrode catheter is inserted into a major vein or artery, such as the femoral artery, and then guided into a target heart chamber. A typical ablation procedure involves inserting a catheter with one or more electrodes at its distal end into a heart chamber. A reference electrode is typically taped to the patient's skin or may be provided by a second catheter placed in or near the heart. Radio frequency (RF) current is applied to the tip electrode(s) of the ablation catheter, causing current to flow through the medium surrounding the tip electrode, i.e., blood and tissue, toward the reference electrode. The distribution of the current depends on the amount of electrode surface in contact with the tissue compared to blood, which has a higher electrical conductivity than tissue. Tissue heating occurs due to the electrical resistance of the tissue. Sufficient tissue heating can cause cell destruction in the cardiac tissue, resulting in lesions in the non-conductive cardiac tissue.

[0006] U.S. Patent Publication No. 2018 / 0235537 describes a system for assigning zone rankings to patients. The system includes a processor, at least one database, and a computer-readable medium in communication with the at least one database and including one or more instructions that, when executed, can cause the processor to receive at least one physiological signal from a medical monitoring device worn by the patient, assign a normal zone ranking to the patient based on historical patient data stored in the at least one database, determine one or more metrics from the patient's at least one physiological signal, assign a first zone ranking to the patient based on the one or more metrics, where the first zone ranking is selected from a plurality of abnormal zone rankings stored in the at least one database, determine one or more actions to initiate based on the assigned first zone ranking, and initiate the one or more determined actions.

[0007] U.S. Patent No. 9,560,980 to Charlton et al. describes an implantable medical device (IMD) implanted in a patient. The IMD generates intrathoracic impedance measurements using multiple electrode vectors. The intrathoracic impedance measurements may indicate the amount of intrathoracic fluid in the patient. An accumulation of intrathoracic fluid may indicate that the patient is at high risk for experiencing a heart failure event in the near future. The IMD performs a vector selection operation on an iterative basis. When the IMD performs the vector selection operation, the IMD uses the impedance measurements to select one of the electrode vectors. The IMD may perform a risk assessment operation on another iterative basis. During the risk assessment operation, the IMD uses the impedance measurements of the selected electrode vectors and / or other patient characteristics stored within the IMD to determine whether the patient is at high risk for experiencing a heart failure event.

[0008] U.S. Patent No. 10,314,502 to Peterson et al. describes a system and method for evaluating multiple candidate sensing vectors for use in sensing cardiac electrical activity. The system may sense a physiological signal using each of the multiple candidate sensing vectors and generate a respective signal strength index and interference index using the physiological signal sensed by the respective sensing vectors. The system may also receive electrode information for each of the candidate sensing vectors, including information about sensing electrodes that are also used to deliver cardiac electrical stimulation. The system may rank at least some of the multiple candidate sensing vectors according to the signal strength index, interference index, and electrode information. The system also includes a user interface for displaying the ranked sensing vectors and allowing a user to select at least one sensing vector for use in sensing cardiac electrical activity.

[0009] U.S. Patent No. 10,092,761 to An et al. describes a system and method for evaluating multiple candidate electrical stimulation vectors for use in therapeutic cardiac stimulation. The system may include a programmable electrical stimulator circuit for delivering electrical stimulation to one or more sites of the heart according to the multiple candidate electrical stimulation vectors. One or more physiological sensors may detect a resulting physiological response to the electrical stimulation. A processor circuit may use the sensed physiological response to generate multiple categories of indices, such as a treatment efficacy index, a battery life index, or a complication index. The candidate electrical stimulation vectors may be ranked according to the multiple categories of indices in a specified order. The system may include a user interface for displaying the ranked candidate electrical stimulation vectors, allowing a user to select one or more electrical stimulation vectors, and programming the electrical stimulation circuit to deliver therapeutic electrical stimulation to at least one site of the heart using the selected electrical stimulation vector.

[0010] U.S. Patent Publication No. 2010 / 0198292 to Honeck et al. describes techniques that include delivering cardiac pacing therapy from a medical device to a heart chamber via a first electrode configuration and determining that delivery of cardiac pacing therapy via the first electrode configuration does not adequately capture the heart chamber. In response to such a determination, the medical device delivers cardiac pacing therapy to the heart chamber via multiple additional electrode configurations. These techniques further include determining capture characteristics for each of the additional electrode configurations based on delivery of cardiac pacing therapy to the heart chamber via multiple other electrode configurations. New electrode configurations for cardiac pacing can be selected based on the capture characteristics of the various electrode configurations.

[0011] U.S. Patent Publication No. 2016 / 0166166 to Bunch et al. describes a method for treating a cardiac complex rhythm disorder in a patient, including receiving a plurality of electrical signals from a sensor system, each electrical signal corresponding to a distinct location on a cardiac wall of the patient's heart, each electrical signal including an electrogram waveform, and ranking the electrical signals relative to one another based on at least the uniformity and frequency of the electrogram waveform of each electrical signal. Summary of the Invention [Means for solving the problem]

[0012] According to one embodiment of the present invention, there is provided a medical treatment system including: a first electrode including a probe configured for insertion into a heart chamber of a living subject, the first electrode configured to apply a series of pacing pulses at a location within the heart chamber; a second electrode configured to sense electrical activation signals in response to electrical activations induced by capturing the pacing pulses over time within the myocardium of the heart chamber; a display; and a processing circuit configured to: evaluate successful capture of the induced electrical activations in response to the electrical activation signals by the second electrode, where successful capture indicates successful capture of the pacing pulses by the myocardium; calculate a capture grade in response to the evaluation of the successful capture of the induced electrical activations, where the capture grade indicates a number of induced electrical activations assessed as successfully captured; and render the capture grade on the display.

[0013] Furthermore, according to one embodiment of the present invention, the processing circuitry is configured to evaluate successful acquisition by the second electrode of each of the electrical activations induced by each of the pacing pulses in response to an electrical activation signal exceeding a threshold signal amplitude within a given time frame after each of the pacing pulses.

[0014] Still further, in accordance with an embodiment of the present invention, the processing circuitry is configured to calculate a capture grade in response to the number of evoked electrical activations assessed as successfully acquired by the second electrode.

[0015] Additionally, in accordance with one embodiment of the present invention, the processing circuitry is configured to calculate the capture grade also in response to the number of missing electrical activations.

[0016] Moreover, according to one embodiment of the present disclosure, the processing circuitry is configured to calculate the capture grade also in response to the total number of pacing pulses.

[0017] Furthermore, in accordance with one embodiment of the present invention, the processing circuitry is configured to calculate a capture grade in response to the number of missed electrical activations and the total number of pacing pulses.

[0018] Still further, in accordance with one embodiment of the present invention, the system includes a pacing unit configured to generate pacing pulses for application by the first electrode.

[0019] Additionally, according to one embodiment of the present invention, the processing circuitry is configured to render the capture grade on a display using a representation of the electrical activation signal.

[0020] Moreover, according to one embodiment of the present disclosure, the processing circuitry is configured to track the location of the second electrode.

[0021] Furthermore, in accordance with an embodiment of the present invention, the processing circuitry is configured to render different representations of the probe on the display depending on the tracked location.

[0022] According to another embodiment of the present invention, there is provided a medical procedure method including inserting a first probe into a cardiac chamber of a living subject; applying a series of pacing pulses at a location within the cardiac chamber using a first electrode of the first probe; sensing an electrical activation signal in response to electrical activation induced by capturing the pacing pulses over time within the myocardium of the cardiac chamber using a second electrode; evaluating successful capture of the induced electrical activation by the second electrode in response to the electrical activation signal, where successful capture indicates successful capture of the pacing pulse by the myocardium; calculating a capture grade in response to the evaluation of the successful capture of the induced electrical activation, where the capture grade indicates a number of induced electrical activations assessed as successfully captured; and rendering the capture grade on a display.

[0023] Still further, in accordance with an embodiment of the present invention, the evaluating includes evaluating successful acquisition by the second electrode of each of the electrical activations induced by each of the pacing pulses in response to an electrical activation signal exceeding a threshold signal amplitude within a given time frame after each of the pacing pulses.

[0024] Additionally, according to one embodiment of the present invention, the calculating includes calculating a capture grade in response to the number of evoked electrical activations assessed as successfully acquired by the second electrode.

[0025] Moreover, according to one embodiment of the present invention, calculating also includes calculating the capture grade in response to the number of missing electrical activations.

[0026] Furthermore, in accordance with one embodiment of the present invention, the calculating also includes calculating the capture grade in response to a total number of pacing pulses.

[0027] Still further, in accordance with an embodiment of the present invention, the calculating includes calculating a capture grade in response to the number of missed electrical activations and the total number of pacing pulses.

[0028] Additionally, according to one embodiment of the present invention, the method includes generating a pacing pulse for application by the first electrode.

[0029] Furthermore, in accordance with an embodiment of the present invention, the rendering includes rendering the capture grade on a display using a representation of the electrical activation signal.

[0030] Furthermore, according to an embodiment of the present disclosure, the method includes tracking a location of the second electrode.

[0031] Still further, in accordance with an embodiment of the present invention, the rendering includes rendering a representation of another probe on the display in response to the tracked location. [Brief explanation of the drawings]

[0032] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a schematic illustration of a medical treatment system constructed and operative in accordance with an exemplary embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram of a catheter for use in the system of FIG. 1. [Figure 3] FIG. 2 is a schematic diagram of an intracardiac electrogram generated by the system of FIG. 1. [Figure 4] FIG. 4 is a schematic diagram of a portion of the intracardiac electrogram of FIG. 3. [Figure 5] FIG. 2 is a schematic diagram of a user interface generated by the system of FIG. 1. [Figure 6] 2 is a flow diagram including steps in a method of operating the medical treatment system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0033] Overview Pacing signals may be used in mapping a heart chamber, in preparation for mapping a heart chamber, or in preparation for other medical procedures. For example, pacing signals can be used to map conduction pathways and identify abnormal conduction pathways. Additionally or alternatively, a physician can observe electrical activation signals (induced by pacing) captured by the myocardium of a heart chamber to determine whether an electrode(s) is / are securely placed within the heart chamber. Electrode placement security may refer to the placement of the electrode applying the pacing signal and / or the electrode sensing the electrical activity induced by the pacing signal. After an electrode is determined to be securely placed within a heart chamber, the electrode may be used for mapping or ablation, or any suitable medical procedure. However, visually analyzing electrical activation signals is a meticulous and lengthy process. This is particularly important during time-critical medical procedures, such as cardiac procedures. Moreover, when a catheter includes multiple electrodes, which may include tens or even hundreds of electrodes, the visual analysis task may be too burdensome to perform effectively.

[0034] An exemplary embodiment of the present invention solves the above problem by providing a system that automatically evaluates successful acquisition by an electrode of electrical activations induced by a series of pacing pulses in response to an electrical activation signal. Successful acquisition indicates successful capture of the pacing pulse by the myocardium. The system also calculates a capture grade indicating the number of electrical activations evaluated as successfully acquired. The capture grade provides a quantitative and / or descriptive measure of how well the electrode acquired the electrical activations, and thus a measure of how securely the electrode is positioned within the heart chamber and / or a measure of how well the myocardium captured the pacing pulse. For example, if one out of five electrical activations is acquired, the score may be “low,” or “poor,” or “1,” or “20%.” If four out of five electrical activations are acquired, the score may be “high,” or “excellent,” or “4,” or “80%.” The quantitative and / or descriptive measures provide the physician with an immediate assessment of the security of placement of the sensing and / or pacing application electrodes without the need for manual visual analysis of the electrical activation signal. The above may be repeated for additional electrodes on the probe.

[0035] The quantitative and / or descriptive measures may be used by a physician to grade the quality of the electrodes for mapping (and / or pacing) so that the physician can confidently map (and / or pace) or perform some other task such as determining the quality of tissue contact for ablation.

[0036] In some exemplary embodiments, a medical treatment system includes a first probe inserted into a cardiac chamber of a living subject and a second probe inserted into the cardiac chamber. In some exemplary embodiments, the first and second probes may be combined into a single catheter. In some exemplary embodiments, the second probe may be replaced by one or more body surface electrodes for sensing electrical activation signals.

[0037] The system includes a pacing unit that generates a series of pacing pulses for application by a "first" electrode of a first probe at a location within a heart chamber (e.g., the coronary sinus) to induce a corresponding series of electrical activations over time within the myocardium of the heart chamber, and a "second" electrode (of a second probe) that senses an electrical activation signal in response to the series of electrical activations.

[0038] The system also includes a processing circuit that tracks the location of the second electrode. In some exemplary embodiments, the processing circuit may also track the location of the first electrode and / or one or more additional electrodes of the second probe.

[0039] The processing circuit evaluates successful acquisition of the electrical activation by the second electrode in response to the electrical activation signal. Successful acquisition indicates successful capture of the pacing pulse by the myocardium. This may be repeated for more electrodes of the second probe. In some exemplary embodiments, the processing circuit evaluates successful acquisition of each of the electrical activations induced by each of the pacing pulses by the second electrode in response to the amplitude of the electrical activation signal exceeding a threshold signal amplitude within a given time frame after each pacing pulse.

[0040] The processing circuit calculates a capture grade for the second electrode in response to evaluating each successful acquisition of the electrical activations. The capture grade indicates the number of electrical activations evaluated as successfully acquired by the second electrode. This may also be repeated for other electrodes of the second probe. In some exemplary embodiments, the processing circuit calculates the capture grade in response to the number of evoked electrical activations and the number of unacquired electrical activations or the total number of pacing pulses evaluated as successfully acquired by the second electrode. In other exemplary embodiments, the processing circuit calculates the capture grade in response to the number of unacquired electrical activations and the total number of pacing pulses.

[0041] The processing circuitry may render the capture grade on a display, which may also be rendered with a representation of the corresponding electrical activation signal. The processing circuitry may also render a representation of the second probe on a display in response to the tracked location.

[0042] System Description Reference is now made to Figure 1, which is a schematic illustration of a medical procedure system 20 constructed and operative in accordance with an exemplary embodiment of the present invention. Reference is also made to Figure 2, which is a schematic illustration of a catheter 40 for use in the system 20 of Figure 1.

[0043] The medical treatment system 20 is used to determine the position of a catheter 40, shown in inset 25 of Figure 1 and in more detail in Figure 2. The catheter 40 is a probe that includes a shaft 22 and a plurality of deflectable arms 54 (only some of which are labeled for simplicity) for insertion into a body part (e.g., a chamber of the heart 26) of a living subject. The deflectable arms 54 have respective proximal ends connected to the distal end of the shaft 22.

[0044] The catheter 40 includes a position sensor 53 disposed on the shaft 22 in a predetermined spatial relationship with respect to the proximal end of the deflectable arm 54. The position sensor 53 may include a magnetic sensor 50 and / or at least one shaft electrode 52. The magnetic sensor 50 may include at least one coil, such as, but not limited to, a two-axis or three-axis coil arrangement, to provide position and orientation position data, including rotation. The catheter 40 includes multiple electrodes 55 (only some of which are labeled in FIG. 2 for simplicity) disposed at different respective positions along each of the deflectable arms 54. Typically, the catheter 40 may be used to map electrical activity within a living subject's heart using the electrodes 55, or to perform any other suitable function within a body part of a living subject, such as, but not limited to, reversible and / or irreversible electroporation and / or RF ablation.

[0045] The medical procedure system 20 may determine the position and orientation of the shaft 22 of the catheter 40 based on signals provided by the magnetic sensor 50 and / or shaft electrodes 52 (proximal electrode 52 a and distal electrode 52 b) on either side of the magnetic sensor 50 attached to the shaft 22. The proximal electrode 52 a, the distal electrode 52 b, the magnetic sensor 50, and at least some of the electrodes 55 are connected to various driver circuits within the console 24 via the catheter connector 35 by wires extending through the shaft 22. In some exemplary embodiments, at least two electrodes 55 of each of the deflectable arms 54, the shaft electrodes 52, and the magnetic sensor 50 are connected to driver circuits within the console 24 via the catheter connector 35. In some exemplary embodiments, the distal electrode 52 b and / or the proximal electrode 52 a may be omitted.

[0046] The diagram shown in Figure 2 has been chosen purely for purposes of conceptual clarity. Other configurations of shaft electrode 52 and electrode 55 are possible. Additional functionality may also be included in position sensor 53. For clarity, elements not relevant to the disclosed exemplary embodiment of the invention, such as irrigation ports, have been omitted.

[0047] A physician 30 navigates the catheter 40 to a target location within a body part (e.g., the heart 26) of a patient 28 by using a manipulator 32 near the proximal end of the catheter 40 to manipulate the shaft 22 and / or by deflecting it from the sheath 23. The catheter 40 is inserted through the sheath 23 with the deflectable arms 54 gathered together, and only after the catheter 40 is retracted from the sheath 23 can the deflectable arms 54 unfold and resume their intended functional shape. By containing the deflectable arms 54 together, the sheath 23 also serves to minimize vascular trauma during navigation to the target location.

[0048] Console 24 includes processing circuitry 41, typically a general-purpose computer, and suitable front-end and interface circuitry 44 for generating signals at and / or receiving signals from body surface electrodes 49 attached by wires that extend through cable 39 to the chest and back of patient 28 or any other suitable skin surface.

[0049] Console 24 further includes a magnetic sensing subsystem. Patient 28 is placed within a magnetic field generated by pads including at least one magnetic field emitter 42, which is driven by a unit 43 located on console 24. Magnetic field emitter(s) 42 are configured to transmit an alternating magnetic field into a region where a body part (e.g., heart 26) is located. The magnetic field generated by magnetic field emitter(s) 42 generates a directional signal in magnetic sensor 50. Magnetic sensor 50 is configured to detect at least a portion of the transmitted alternating magnetic field and provide the directional signal as a corresponding electrical input to processing circuitry 41.

[0050] In some exemplary embodiments, processing circuitry 41 uses position signals received from shaft electrode 52, magnetic sensor 50, and electrode 55 to estimate the position of catheter 40 within an organ, such as within a heart chamber. In some exemplary embodiments, processing circuitry 41 correlates the position signals received from electrodes 52 and 55 with previously acquired magnetic position calibration position signals to estimate the position of catheter 40 within the organ. Position coordinates of shaft electrode 52 and electrode 55 may be determined by processing circuitry 41 based on impedance or current distribution percentages measured between electrodes 52, 55, and body surface electrodes 49, among other inputs. Console 24 drives display 27, which shows the distal end of catheter 40 within heart 26.

[0051] Position sensing methods using current distribution measurements and / or external magnetic fields have been used in various medical applications, e.g., by Biosense Webster This technology has been implemented in the Carto® system manufactured by Samsung Electronics Co., Ltd. (Irvine, California) and is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, 6,332,089, 7,756,576, 7,869,865, and 7,848,787, WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1).

[0052] The Carto® 3 system applies an impedance-based position tracking method of active current position (ACL). In some exemplary embodiments, processing circuitry 41 is configured to use the ACL method to create a mapping (e.g., a current position matrix (CPM)) between a representation of electrical impedance and the position in the magnetic coordinate frame of the magnetic field emitter(s) 42. Processing circuitry 41 estimates the positions of shaft electrode 52 and electrode 55 by performing a lookup in the CPM.

[0053] Other methods of determining the position of the distal end of the catheter can be used, for example, using imaging techniques such as ultrasound or MRI or CT scans based on an ultrasound transducer and receiver, which may include placing a radiopaque tag on the catheter 40.

[0054] Processing circuitry 41 is typically programmed in software to carry out the functions described herein, which software may be downloaded to a computer in electronic form, for example over a network, or alternatively or additionally may be provided and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory.

[0055] 1 shows only elements relevant to the disclosed technology for the sake of brevity and clarity. System 20 typically includes additional modules and elements that are not directly related to the disclosed technology and therefore have been intentionally omitted from FIG. 1 and the corresponding description.

[0056] The catheter 40 described above includes eight deflectable arms 54 with six electrodes 55 per arm 54. Any suitable catheter may be used in place of catheter 40, such as, for example, catheters with various numbers of flexible arms and / or multiple electrodes per arm, or various probe geometries, such as, by way of example, a balloon catheter or a lasso catheter.

[0057] Medical treatment system 20 may also perform electroporation or RF ablation (or other ablation techniques) of cardiac tissue using any suitable catheter, such as catheter 40 or a different catheter, and any suitable ablation method. Console 24 may include a signal generator 34 configured to generate an electrical signal applied by electrode(s) of a catheter connected to console 24 (and, optionally, one or more of body surface electrodes 49) to perform electroporation or RF ablation of the myocardium of heart 26. Console 24 may include a pump (not shown) that pumps irrigation fluid through an irrigation channel to the distal end of the catheter performing RF ablation. The catheter performing RF ablation may further include a temperature sensor (not shown) that is used to measure the temperature of the myocardium during RF ablation and adjust the ablation power and / or the irrigation rate of pumped irrigation fluid according to the measured temperature.

[0058] System 20 may also include a probe 36 configured to be inserted into a chamber of heart 26 and including electrodes 38. Probe 36 may be implemented as part of catheter 40 or as part of a different catheter. System 20 also includes a pacing unit 46 disposed within console 24 and configured to generate a series of pacing pulses for application by electrodes 38, as will be described in more detail with reference to FIGS. 3-6 .

[0059] Reference is now made to FIG. 3, which is a schematic illustration of an intracardiac electrogram 60 generated by system 20 of FIG. 1. Intracardiac electrogram 60 is annotated to show the timing of pacing pulses 62 applied to the myocardium to induce electrical activation of the myocardium, shown as signal peaks 64. Intracardiac electrogram 60 includes two large peaks 64-1 and 64-4 following pacing pulses 62-1 and 62-4, respectively. Peaks 64-1 and 64-4 exceed the threshold signal amplitude 66. Peak 64-2 following pacing pulse 62-2 is much smaller than large peaks 64-1 and 64-4 and is below the threshold signal amplitude 66. There is no peak following pacing pulse 62-3. Thus, from the four pacing pulses 62, two electrical activations were acquired by electrodes 55 (FIG. 2) that provided intracardiac electrogram 60. Electrode 55 may be assigned a capture grade of 50%, or (2 out of 4), or "fair." Another one of the electrodes may capture four electrical activations and may be given a capture grade of 100%, or (4 out of 4), or "excellent," for example. If one electrode has a capture grade of 100%, meaning that all of the pacing pulses were captured by the heart's myocardium, the other electrode has a capture grade of 50%, meaning that some of the electrical activations were not captured due to electrode misplacement.

[0060] Reference is now made to FIG. 4, which is a schematic illustration of a portion of the intracardiac electrogram 60 of FIG. 3, showing a peak 64-1 following a pacing pulse 62-1. The processing circuitry 41 (FIG. 1) is configured to evaluate successful acquisition of the electrical activation evoked by a given electrode 55 (FIG. 2) in response to an electrical activation signal (e.g., the intracardiac electrogram 60) exceeding a threshold signal amplitude 66 within a given time frame 68 after the pacing pulse 62-1. FIG. 4 shows that the intracardiac electrogram 60 exceeds the threshold signal amplitude 66 within the time frame 68. The time frame 68 may have any suitable value, for example, in the range of 0.04 to 0.3 seconds. The threshold signal amplitude 66 may have any suitable amplitude, for example, in the range of 0.5 to 1.5 mV.

[0061] Reference is now made to FIG. 5, which is a schematic diagram of a user interface 70 generated by system 20 of FIG. 1. FIG. 5 shows two intracardiac electrograms 60-1, 60-2 sensed by two respective ones of electrodes 55 (FIG. 2) rendered on display 27. A respective capture grade 72 is displayed alongside each intracardiac electrogram 60-1, 60-2. Intracardiac electrogram 60-1 indicates that two electrical activations above the threshold were acquired by each electrode 55, and thus a capture grade 72 of 50% is assigned. Intracardiac electrogram 60-2 indicates that four electrical activations above the threshold were acquired by electrode 55, and thus a capture grade 72 of 100% is assigned. FIG. 5 also shows a representation of catheter 40 within a chamber of heart 26, with two of the electrodes marked with annotations 74 indicating the number assigned to each electrode.

[0062] Reference is now made to FIG. 6, which is a flow diagram 80 including steps in a method of operating the medical treatment system 20 of FIG. 1. Reference is also made to FIG. 1. A physician 30 inserts a probe 36 into a chamber of a heart 26 of a living subject (e.g., patient 28) (block 82). The physician 30 also inserts another probe (e.g., part of a catheter 40) into the chamber (block 82). For clarity, the following description will refer to the other probe as catheter 40. The probe 36 may be provided as part of the catheter 40 or as part of a different catheter. In some exemplary embodiments, instead of inserting a separate probe, the physician 30 applies one or more body surface electrodes to the tissue surface of the patient 28.

[0063] Processing circuitry 41 is optionally configured to track (block 84) the location of one of electrodes 55 ( FIG. 2 ) (hereinafter referred to as “electrode 55”). Processing circuitry 41 may track the location of electrode 55 using any suitable position tracking method, such as one of the methods described above with reference to FIG. 1. Processing circuitry 41 may optionally track the location of electrode 55 and / or other of electrodes 38 of probe 36.

[0064] The pacing unit 46 is configured to generate pacing pulses for application by the electrodes 38 of the probe 36 (block 86). In response, the electrodes 38 are configured to apply a series of pacing pulses 62 (FIG. 3) at locations within the heart chamber (block 88) to induce a corresponding series of electrical activations in the myocardium of the heart chamber over time. The electrodes 55 (or body surface electrodes) of the catheter 40 are configured to sense electrical activation signals 60 (FIG. 3) (block 90) in response to the electrical activations induced by capturing the pacing pulses in the myocardium of the heart chamber over time. Other electrodes 55 of the catheter 40 may also be configured to sense respective electrical activation signals in response to the electrical activations induced by capturing the pacing pulses in the myocardium of the heart chamber over time.

[0065] Processing circuitry 41 is configured to evaluate (block 92) successful acquisition of evoked electrical activation by electrodes 55 (or body surface electrodes) in response to electrical activation signal 60. In some exemplary embodiments, processing circuitry 41 is configured to evaluate successful acquisition by electrodes 55 of each of the electrical activations evoked by each of pacing pulses 62 in response to the amplitude of electrical activation signal 60 exceeding threshold signal amplitude 66 (FIG. 4) within a given time frame 68 (FIG. 4) after each pacing pulse 62. The above steps may also be performed for each electrical activation signal of each of the other ones of electrodes 55.

[0066] The processing circuitry 41 is configured to calculate (block 94) a capture grade 72 (FIG. 5) for the electrode 55 (or body surface electrode) in response to assessing successful acquisition of evoked electrical activations by the electrode 55. The capture grade generally indicates the number of evoked electrical activations assessed as successfully acquired by the electrode 55. The steps of block 94 may be repeated for other electrodes 55 of the catheter 40. The capture grade may be calculated based on the number of successfully acquired and missed electrical activations (e.g., expected to occur within a time window after each pacing pulse), or the number of successfully acquired electrical activations and the total number of pacing pulses, or the number of missed electrical activations and the total number of pacing pulses. Thus, the processing circuitry 41 may be configured to calculate the capture grade in response to the number of evoked electrical activations assessed as successfully acquired by the electrode 55 and as missed by the electrode 55, or in response to the total number of pacing pulses. In some exemplary embodiments, processing circuitry 41 is configured to calculate a capture grade in response to the number of missed electrical activations and the total number of pacing pulses. The capture grade may be expressed as a quantitative measure, such as a score or percentage of successful acquisitions out of the total number of electrical activations, or as a descriptive measure, such as "very poor" if the capture grade is 20% or less, "poor" if the capture grade is 20% or more but less than 40%, "fair" if the capture grade is 40% or more but less than 60%, "good" if the capture grade is 60% or more but less than 80%, and "excellent" if the capture grade is greater than 80%. The descriptions and associated ranges are provided by way of example only, and any suitable descriptions and associated ranges may be used.

[0067] As shown in FIG. 5 , processing circuitry 41 is configured to render capture grades 72 on display 27 (block 96). In some exemplary embodiments, processing circuitry 41 is configured to render capture grades 72 on display 27 using a representation of electrical activation signals 60, as shown in FIG. 5 . In some embodiments, processing circuitry 41 is configured to render a representation of catheter 40 on display 27 in response to the tracked location(s). Each capture grade 72 and, optionally, each intracardiac electrogram 60 for each electrode 55 may be rendered on display 27. Catheter 40 may be rendered on display 27 along with annotations 74 ( FIG. 5 ) indicating the electrode numbers assigned to the electrodes 55.

[0068] The term "about" or "approximately" used herein in connection with any numerical value or range of values ​​indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function according to its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value; for example, "about 90%" may refer to a range of values ​​of 72% to 108%.

[0069] Various features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single exemplary embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0070] The above-described embodiments are cited by way of example, and the present invention is not limited to what has been particularly shown and described in the foregoing specification. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof that would occur to those skilled in the art upon reading the foregoing description, but which are not disclosed in the prior art.

[0071] [Embodiment] (1) A medical treatment system comprising: a probe configured for insertion into a heart chamber of a living subject, the probe including a first electrode configured to apply a series of pacing pulses at a location within the heart chamber; a second electrode configured to sense an electrical activation signal in response to electrical activation induced by capturing the pacing pulses over time within the myocardium of the heart chamber; and The display and A processing circuit, the processing circuit comprising: assessing successful acquisition of the evoked electrical activation by the second electrode in response to the electrical activation signal, the successful acquisition indicating successful capture of the pacing pulse by the myocardium; calculating a capture grade in response to the evaluation of the successful acquisition of the evoked electrical activation, the capture grade indicating the number of times the evoked electrical activation was evaluated as being successfully acquired; and rendering the capture grade on the display. (2) The system described in embodiment 1, wherein the processing circuit is configured to evaluate the successful acquisition of each of the electrical activations induced by each of the pacing pulses by the second electrode in response to the electrical activation signal exceeding a threshold signal amplitude within a given time frame after each of the pacing pulses. (3) The system of embodiment 1, wherein the processing circuit is configured to calculate the capture grade in response to the number of times the evoked electrical activation is evaluated as being successfully acquired by the second electrode. (4) The system of embodiment 3, wherein the processing circuitry is configured to calculate the capture grade also in response to a number of missed electrical activations. (5) The system described in embodiment 3, wherein the processing circuit is configured to calculate the capture grade also in response to the total number of the pacing pulses.

[0072] (6) The system of embodiment 1, wherein the processing circuit is configured to calculate the capture grade in response to the number of unacquired electrical activations and the total number of pacing pulses. (7) The system described in embodiment 1, further comprising a pacing unit configured to generate the pacing pulse for application by the first electrode. (8) The system of embodiment 1, wherein the processing circuitry is configured to render the capture grade on the display using a representation of the electrical activation signal. (9) The system of embodiment 1, wherein the processing circuit is configured to track the location of the second electrode. (10) The system of embodiment 9, wherein the processing circuit is configured to render a representation of another probe on the display in response to the tracked location.

[0073] (11) A medical treatment method comprising: inserting a first probe into a cardiac chamber of a living subject; applying a series of pacing pulses at a location within the heart chamber using a first electrode of the first probe; sensing, with a second electrode, an electrical activation signal in response to electrical activation induced by capturing the pacing pulse over time within the myocardium of the heart chamber; assessing successful acquisition of the evoked electrical activation by the second electrode in response to the electrical activation signal, the successful acquisition indicating successful capture of the pacing pulse by the myocardium; calculating a capture grade in response to the evaluation of the successful acquisition of the evoked electrical activation, the capture grade indicating the number of times the evoked electrical activation was evaluated as being successfully acquired; and rendering the capture grade on a display. (12) The method of embodiment 11, wherein the evaluating includes evaluating the successful acquisition by the second electrode of each of the electrical activations induced by each of the pacing pulses in response to the electrical activation signal exceeding a threshold signal amplitude within a given time frame after each of the pacing pulses. (13) The method of embodiment 11, wherein the calculating step includes calculating the capture grade in response to a number of the evoked electrical activations assessed as successfully acquired by the second electrode. (14) The method of embodiment 13, wherein the calculating step also includes calculating the capture grade in response to a number of missed electrical activations. (15) The method of embodiment 13, wherein the calculating step also includes calculating the capture grade in response to a total number of the pacing pulses.

[0074] (16) The method of embodiment 11, wherein the calculating step includes calculating the capture grade in response to a number of unacquired electrical activations and a total number of the pacing pulses. (17) The method of embodiment 11, further comprising generating the pacing pulse for application by the first electrode. (18) The method of embodiment 11, wherein the rendering includes rendering the capture grade on the display using a representation of the electrical activation signal. (19) The method of embodiment 11, further comprising tracking the location of the second electrode. (20) The method of embodiment 19, wherein the rendering includes rendering a representation of another probe on the display in response to the tracked location.

Claims

1. 1. A medical treatment system comprising: a first probe configured for insertion into a heart chamber of a living subject, the first probe including a first electrode configured to apply a series of pacing pulses at a location within the heart chamber; a second probe including a plurality of second electrodes configured to sense electrical activation signals in response to electrical activation induced by capturing the pacing pulses over time within the myocardium of the heart chamber; and The display and a processing circuit configured to track locations of the plurality of second electrodes; calculating a capture grade for each of the plurality of second electrodes using a number of evoked electrical activations, which is the number of times the amplitude of the electrical activation signal exceeds a threshold signal amplitude within a given time window after each of the pacing pulses; Rendering on the display a representation of the interior of the heart chamber of a second probe including the plurality of second electrodes in response to the tracked locations; and rendering a capture grade of each of the plurality of second electrodes on the display.

2. 2. The system of claim 1, wherein the processing circuitry is configured to render the grade of capture on the display along with an intracardiac electrogram based on the electrical activation signals used to calculate the grade of capture.

3. 3. The system of claim 1, wherein the processing circuitry is configured to render on the display an annotation indicating the corresponding second electrode along with the representation of the capture grade, and to render on the display an annotation indicating the corresponding second electrode along with each of the plurality of second electrodes of the representation of the second probe.

4. 2. The system of claim 1, wherein the processing circuitry is configured to also use a number of missed electrical activations, which is the number of times the amplitude of the electrical activation signal within a given time window after each pacing pulse does not exceed the threshold signal amplitude, to calculate the capture grade.

5. 2. The system of claim 1, wherein the processing circuitry is configured to also use a total number of the pacing pulses to calculate the capture grade.

6. 5. The system of claim 4, wherein the processing circuitry is configured to also use a total number of the pacing pulses to calculate the capture grade.

7. The system of claim 1 , further comprising a pacing unit configured to generate the pacing pulses for application by the first electrode.

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