Pacing-induced electrical activation grade

Abstract

The present invention is entitled "Grading of Pacing-Induced Electrical Activation." In one embodiment, a medical procedure system includes: a probe for insertion into a cardiac chamber of a living subject and including a first electrode for applying a pacing pulse sequence at a location in the chamber; a second electrode for sensing an electrical activation signal in response to capturing electrical activation induced by the pacing pulse in myocardium of the chamber; a display; and processing circuitry for assessing successful acquisition of the induced 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 assessment of successful acquisition of the induced electrical activation, the capture grade indicating a count of the induced electrical activations assessed as successfully acquired, and presenting the capture grade to the display.

Description

Technical Field

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

[0002] A large number of medical procedures involve placing probes such as catheters in the patient's body. Position sensing systems have been developed to track such probes. Magnetic position sensing is a method known in the art. In magnetic position sensing, a magnetic field generator is usually placed at a known position 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 electrical signals are processed to determine the coordinate position of the distal end of the probe. These methods and systems are described in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, in PCT International Patent Publication WO1996 / 005768, and in U.S. Patent Application Publication 2002 / 006455, 2003 / 0120150, and 2004 / 0068178. Systems based on impedance or current can also be used to track position.

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

[0004] The diagnosis and treatment of cardiac arrhythmias include mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volume, and selectively ablating cardiac tissue by applying energy. Such ablation can stop or alter the propagation of unwanted electrical signals from one part of the heart to another. Ablation methods destroy unwanted electrical pathways by forming non-conductive lesions. Various forms of energy delivery for forming lesions have been disclosed, and include the use of microwaves, lasers, and more commonly, radiofrequency energy to form conduction blocks along the walls of cardiac tissue. In a two-step procedure (mapping followed by ablation), electrical activity at various points within the heart is typically sensed and measured by advancing a catheter containing one or more electrical sensors into the heart and collecting data at multiple points. This data is then used to select a target area of ​​the endocardium to be ablated.

[0005] Electrode catheters have been commonly used in medical practice for many years. They are used to stimulate and map electrical activity in the heart, as well as 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 the heart chamber of interest. A typical ablation procedure involves inserting a catheter having one or more electrodes at its distal end into the heart chamber. A reference electrode, usually taped to the patient's skin, may be provided, or a second catheter placed in or near the heart may be used to provide the reference electrode. RF (radio frequency) current is applied to the tip electrode of the ablation catheter, and the current flows to the reference electrode through the surrounding medium (i.e., blood and tissue). The distribution of the current depends on the amount of contact between the electrode surface and the tissue compared to blood, which has a higher conductivity than tissue. Due to the electrical resistance of the tissue, heating of the tissue occurs. The tissue is heated sufficiently to cause cell destruction in the cardiac tissue, resulting in the formation of non-conductive ablation lesions within the cardiac tissue.

[0006] US Patent Publication No. 2018 / 0235537 describes a system for assigning a zone order to a patient. The system includes a processor, at least one database, and a computer-readable medium in communication with the at least one database and comprising one or more instructions that, when executed, cause the processor to receive at least one physiological signal from a medical monitoring device worn by a patient; assign a normal zone order to the patient based on historical patient data stored in the at least one database; determine one or more metrics based on the at least one physiological signal of the patient; assign a first zone order to the patient based on the one or more metrics, the first zone order being selected from a plurality of abnormal zone orders stored in the at least one database; determine one or more actions to be initiated based on the assigned first zone order; and initiate the one or more determined actions.

[0007] U.S. Patent 9,560,980 to Charlton et al. describes an implantable medical device (IMD) that is implanted in a patient. The IMD uses multiple electrode vectors to generate intrathoracic impedance measurements. The intrathoracic impedance measurements may indicate the amount of intrathoracic fluid in the patient. The accumulation of intrathoracic fluid may indicate that the patient is at an increased risk of experiencing a heart failure event in the near future. The IMD performs a vector selection operation on a repeated 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 repeated basis. During the risk assessment operation, the IMD uses the impedance measurements of the selected electrode vectors and / or other patient characteristics stored in the IMD to determine whether the patient is at an increased risk of experiencing a heart failure event.

[0008] U.S. Patent 10,314,502 to Peterson et al. describes a system and method for evaluating multiple candidate sensing vectors for sensing electrical activity of the heart. The system may use each of the multiple candidate sensing vectors to sense a physiological signal, and use the physiological signal sensed using the corresponding sensing vector to generate a corresponding signal strength indicator and an interference indicator. 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 sort at least some of the multiple candidate sensing vectors based on the signal strength indicator, interference indicator, and electrode information. The system may also include a user interface for displaying the sorted sensing vectors and allowing a user to select at least one sensing vector for sensing cardiac electrical activity.

[0009] U.S. Patent 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 multiple candidate electrical stimulation vectors. One or more physiological sensors may detect a resulting physiological response to the electrical stimulation. The processor circuit may use the sensed physiological response to generate an indicator category, the indicator including a therapeutic efficacy indicator, a battery life indicator, or a complex function block indicator. The candidate electrical stimulation vectors may be sorted according to the category of the indicator in a specified order. The system may include a user interface for displaying the sorted candidate electrical stimulation vectors and allowing a user to select one or more electrical stimulation vectors and programming the electrical stimulator circuit to deliver therapeutic electrical stimulation to at least one site of the heart using the selected electrical stimulation vectors.

[0010] U.S. Patent Publication 2010 / 0198292 to Honeck et al. describes a technique that includes delivering cardiac pacing therapy from a medical device to a cardiac chamber via a first electrode configuration and determining that cardiac pacing therapy delivered via the first electrode configuration has insufficient capture of the chamber. In response to such determination, the medical device delivers cardiac pacing therapy to the cardiac chamber via a plurality of additional electrode configurations. The technique also includes determining a capture characteristic of each of the additional electrode configurations based on delivering cardiac pacing therapy to the cardiac chamber via the plurality of other electrode configurations. A new electrode configuration for cardiac pacing can be selected based on the capture characteristics of the various electrode configurations.

[0011] U.S. Patent Publication 2016 / 0166166 to Bunch et al. describes a method for treating a cardiac rhythm disorder in a patient, comprising receiving a plurality of electrical signals from a sensor system, wherein each electrical signal corresponds to a separate location on a wall of the patient's heart and wherein each electrical signal includes an electrogram waveform; and ordering the electrical signals relative to each other based at least on a uniformity and a frequency of the electrogram waveform of each electrical signal. Summary of the Invention

[0012] According to an embodiment of the present invention, a medical procedure system is provided, which includes: a probe configured to be inserted into a cardiac chamber of a living subject and including a first electrode configured to apply a pacing pulse sequence at a certain location in the chamber; a second electrode configured to sense an electrical activation signal in response to electrical activation induced by capturing the pacing pulse in the myocardium of the chamber over time; a display; and a processing circuit configured to evaluate the successful acquisition of the induced 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, calculate a capture level in response to the evaluation of the successful acquisition of the induced electrical activation, the capture level indicating a count of the induced electrical activations evaluated as successfully acquired, and present the capture level to the display.

[0013] Further in accordance with an embodiment of the present invention, the processing circuit is configured to evaluate successful acquisition of a corresponding electrical activation in the electrical activation induced by the corresponding pacing pulse in the pacing pulse by the second electrode pair in response to the electrical activation signal exceeding a threshold signal amplitude within a given time window after the corresponding pacing pulse.

[0014] Further in accordance with an embodiment of the present invention, the processing circuit is configured to calculate a capture level in response to the counts of induced electrical activations assessed as successfully acquired by the second electrode.

[0015] Additionally, in accordance with an embodiment of the present invention, the processing circuit is configured to calculate the capture level also in response to the count of uncollected electrical activations.

[0016] Furthermore, in accordance with an embodiment of the present invention, the processing circuit is configured to calculate the capture level also in response to the total count of pacing pulses.

[0017] Further in accordance with an embodiment of the present invention, the processing circuit is configured to calculate the capture level in response to the count of unacquired electrical activations and the total count of pacing pulses.

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

[0019] Additionally, in accordance with an embodiment of the present invention, the processing circuit is configured to present the capture level with a representation of the electrical activation signal to the display.

[0020] Furthermore, in accordance with an embodiment of the present invention, the processing circuit is configured to track the position of the second electrode.

[0021] Further in accordance with an embodiment of the present invention, the processing circuit is configured to present a representation of the other probe to the display in response to the tracked position.

[0022] According to another embodiment of the present invention, a medical procedure method is also provided, which includes inserting a first probe into a cardiac chamber of a living subject, applying a pacing pulse sequence at a certain position in the chamber with a first electrode of the first probe, sensing an electrical activation signal with a second electrode in response to electrical activation induced by capturing the pacing pulse in the myocardium of the chamber over time, evaluating successful acquisition of the induced electrical activation by the second electrode in response to the electrical activation signal, the successful acquisition indicating that the myocardium successfully captured the pacing pulse, calculating a capture level in response to the evaluation of the successful acquisition of the induced electrical activation, the capture level indicating a count of the induced electrical activations evaluated as successfully acquired, and presenting the capture level to a display.

[0023] Further in accordance with an embodiment of the present invention, the evaluation includes evaluating the successful acquisition of the corresponding electrical activation induced by the corresponding pacing pulse in the pacing pulse by the second electrode pair in response to the electrical activation signal exceeding a threshold signal amplitude within a given time window after the corresponding pacing pulse.

[0024] Additionally, in accordance with an embodiment of the present invention, calculating includes calculating a capture level in response to the count of induced electrical activations assessed as successfully acquired by the second electrode.

[0025] Furthermore, according to an embodiment of the present invention, the calculating further comprises calculating the capture level also in response to the counts of electrical activations that were not acquired.

[0026] Further in accordance with an embodiment of the present invention, calculating further comprises calculating the capture level also in response to the total count of pacing pulses.

[0027] Further in accordance with an embodiment of the present invention, calculating includes calculating a capture level responsive to the count of unacquired electrical activations and the total count of pacing pulses.

[0028] Additionally, in accordance with an embodiment of the present invention, the method includes generating a pacing pulse for application to the first electrode.

[0029] Furthermore, in accordance with an embodiment of the present invention, presenting includes presenting the captured level with the representation of the electrical activation signal to a display.

[0030] According further to an embodiment of the present invention, the method includes tracking the position of the second electrode.

[0031] Further in accordance with an embodiment of the present invention, presenting includes presenting to the display a representation of another probe responsive to the tracked position. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0033] Figure 1 is a schematic diagram of a medical protocol system constructed and operative in accordance with an exemplary embodiment of the present invention;

[0034] Figure 2 For use Figure 1 A schematic diagram of a catheter in a system;

[0035] Figure 3 for the reason Figure 1 Schematic diagram of the intracardiac electrogram generated by the system;

[0036] Figure 4 for Figure 3 Schematic diagram of a portion of an intracardiac electrogram;

[0037] Figure 5 for the reason Figure 1 a schematic diagram of a user interface generated by the system; and

[0038] Figure 6 To include Figure 1 A flowchart of steps in a method of operating a medical procedure system. DETAILED DESCRIPTION

[0039] Overview

[0040] The pacing signal can be used to map a cardiac chamber or to prepare for mapping a cardiac chamber or to prepare for other medical procedures. For example, the pacing signal can be used to map a conduction pathway and identify abnormal conduction pathways. In addition or alternatively, the physician can observe the electrical activation signal captured by the myocardium of the cardiac chamber (induced by pacing) to determine whether the electrode is reliably placed in the cardiac chamber. The reliability of electrode placement can refer to the placement of the electrode that applies the pacing signal and / or the electrode that senses the electrical activity induced by the pacing signal. Once it is determined that the electrode is reliably placed in the cardiac chamber, the electrode can be used for mapping or ablation or any suitable medical procedure. However, visually analyzing the electrical activation signal is a meticulous and lengthy process. This is particularly important during time-critical medical procedures (e.g., cardiac procedures). Furthermore, if the catheter includes multiple electrodes, which may include dozens or even hundreds of electrodes, the visual analysis task may become too cumbersome to be performed effectively.

[0041] Exemplary embodiments of the present invention address the aforementioned problems by providing a system that automatically assesses, in response to electrical activation signals, the successful acquisition of electrical activations induced by a pacing pulse sequence by an electrode. Successful acquisition indicates successful capture of the pacing pulse by the myocardium. The system also calculates a capture grade, which indicates a count of electrical activations assessed as successfully acquired. The capture grade provides a quantitative and / or descriptive measure of the degree to which the electrode acquires the electrical activations, and therefore provides a measure of the reliability of the electrode's placement in the cardiac chamber and / or the degree to which the myocardium captures the pacing pulses. For example, if one electrical activation out of every five electrical activations is acquired, the score may be "low," "poor," "1," or "20%," and if four out of every five electrical activations are acquired, the score may be "high," "excellent," "4," or "80%." The quantitative and / or descriptive measures provide the physician with an immediate assessment of the reliability of the placement of the sensing and / or pacing application electrodes without the need for manual visual analysis of the electrical activation signals. The above process may be repeated for additional electrodes in the probe.

[0042] Physicians can use quantitative and / or descriptive metrics to determine the quality level of electrodes used 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.

[0043] In some exemplary embodiments, a medical procedure system includes a first probe inserted into a cardiac chamber of a living subject, and a second probe inserted into the chamber. In some exemplary embodiments, the first probe and the second probe may be combined into a single catheter. In some exemplary embodiments, the second probe may be replaced with one or more body surface electrodes to sense electrical activation signals.

[0044] The system includes a pacing unit that generates a pacing pulse sequence for application by a "first" electrode of a first probe at a location in a chamber (e.g., at the coronary sinus) to induce a corresponding electrical activation sequence in the myocardium of the chamber over time. A "second" electrode (of a second probe) senses an electrical activation signal in response to the electrical activation sequence.

[0045] The system also includes processing circuitry that tracks the position of the second electrode.In some exemplary embodiments, the processing circuitry may also track the position of the first electrode and / or one or more additional electrodes of the second probe.

[0046] The processing circuitry assesses successful acquisition of electrical activation by the second electrode pair in response to the electrical activation signal. Successful acquisition indicates successful capture of the pacing pulse by the myocardium. This process may be repeated for more electrodes of the second probe. In some exemplary embodiments, the processing circuitry assesses successful acquisition of a corresponding one of the electrical activations induced by the corresponding one of the pacing pulses by the second electrode pair in response to the amplitude of the electrical activation signal exceeding a threshold signal amplitude within a given time window after the corresponding pacing pulse.

[0047] The processing circuitry calculates a capture level for the second electrode in response to an assessment of successful acquisition of each of the electrical activations. The capture level indicates a count of electrical activations assessed 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 circuitry calculates the capture level in response to a count of induced electrical activations assessed as successfully acquired by the second electrode, a count of electrical activations that were not acquired, or a total count of pacing pulses. In other exemplary embodiments, the processing circuitry calculates the capture level in response to a count of electrical activations that were not acquired and a total count of pacing pulses.

[0048] The processing circuitry presents the capture level to a display, which may also present a representation of the corresponding electrical activation signal.The processing circuitry may also present a representation of the second probe to the display in response to the tracked position.

[0049] System Description

[0050] Now see Figure 1 , which is a schematic diagram of a medical procedure system 20 constructed and operative in accordance with an exemplary embodiment of the present invention. Figure 2 , which is used for Figure 1 Schematic diagram of the catheter 40 in the system 20.

[0051] The medical procedure system 20 is used to determine the position of the catheter 40, such as in Figure 1 In Figure 25 and in Figure 2 Catheter 40 is a stylet that includes a shaft 22 and a plurality of flexible arms 54 (only some of which are labeled for simplicity) for insertion into a body part of a living subject, such as a chamber of a heart 26. Flexible arms 54 have respective proximal ends connected to the distal end of shaft 22.

[0052] The catheter 40 includes a position sensor 53 disposed on the shaft 22 in a predefined spatial relationship relative to the proximal ends of the flexible arms 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 data of location and orientation (including yaw). The catheter 40 includes a plurality of electrodes 55 (for simplicity, only some are labeled) disposed at different corresponding positions along each of the flexible arms 54. Figure 2 In general, catheter 40 may be used to map electrical activity in the heart of a living subject using electrodes 55, or may be used to perform any other suitable function in a body part of a living subject, such as, but not limited to, reversible and / or irreversible electroporation and / or RF ablation.

[0053] The medical protocol system 20 can determine the position and orientation of the shaft 22 of the catheter 40 based on signals provided by the magnetic sensor 50 and / or the shaft electrodes 52 (proximal electrode 52a and distal electrode 52b) mounted on the shaft 22 and located on either side of the magnetic sensor 50. At least some of the proximal electrode 52a, distal electrode 52b, magnetic sensor 50, and electrodes 55 are connected to various driver circuits in the console 24 via wires extending through the shaft 22 via the catheter connector 35. In some exemplary embodiments, at least two of the electrodes 55 of each of the flexible arms 54, the shaft electrode 52, and the magnetic sensor 50 are connected to the driver circuit in the console 24 via the catheter connector 35. In some exemplary embodiments, the distal electrode 52b and / or the proximal electrode 52a may be omitted.

[0054] Figure 2 The illustrations shown are chosen solely for conceptual clarity. Other configurations of shaft electrode 52 and electrode 55 are possible. Additional functionality may be included in position sensor 53. Elements not relevant to the disclosed exemplary embodiments of the present invention, such as irrigation ports, have been omitted for clarity.

[0055] The physician 30 navigates the catheter 40 to a target location in a body part (e.g., the heart 26) of the patient 28 by manipulating the shaft 22 and / or the deflection of the sheath 23 using the manipulator 32 near the proximal end of the catheter 40. The catheter 40 is inserted through the sheath 23 with the flexible arms 54 gathered together, and only after the catheter 40 is retracted from the sheath 23 are the flexible arms 54 able to unfold and resume their intended functional shape. By holding the flexible arms 54 together, the sheath 23 also serves to minimize vascular trauma on its way to the target site.

[0056] The console 24 includes processing circuitry 41 (typically a general purpose computer) and suitable front-end and interface circuitry 44 for generating signals in and / or receiving signals from body surface electrodes 49, which are attached to the chest and back of the patient 28 or any other suitable skin surface by wires extending through cables 39.

[0057] The console 24 also includes a magnetic sensing subsystem. The patient 28 is placed in a magnetic field generated by a pad including at least one magnetic field radiator 42, which is driven by a unit 43 disposed in the console 24. The one or more magnetic field radiators 42 are configured to emit an alternating magnetic field into the area where the body part (e.g., the heart 26) is located. The magnetic field generated by the one or more magnetic field radiators 42 generates a direction signal in the magnetic sensor 50. The magnetic sensor 50 is configured to detect at least a portion of the emitted alternating magnetic field and provide the direction signal as a corresponding electrical input to the processing circuit 41.

[0058] 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 a heart chamber. In some exemplary embodiments, processing circuitry 41 correlates the position signals received from electrodes 52, 55 with previously acquired magnetic position-calibration position signals to estimate the position of catheter 40 within the organ. The position coordinates of shaft electrode 52 and electrode 55 can be determined by processing circuitry 41 based on (among other inputs) the ratio of current distribution between electrodes 52, 55 and body surface electrode 49 or measured impedance. Console 24 drives display 27, which shows the distal end of catheter 40 within heart 26.

[0059] Methods using current distribution measurements and / or position sensing of external magnetic fields are implemented in various medical applications, for example, in the Magnetic Field Imaging System manufactured by Biosense Webster Inc. (Irvine, California). 5,000,000; and 2,004,000,000. The system is implemented in a 1,000,000,000 system and is described in detail in U.S. Patents 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, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publications 2002 / 0065455 Al, 2003 / 0120150 Al, and 2004 / 0068178 Al.

[0060] The system applies a position tracking method based on active current positioning (ACL) impedance. In some exemplary embodiments, processing circuit 41 is configured to use the ACL method to generate a mapping between an indication of electrical impedance and the position of magnetic field radiator 42 in a magnetic coordinate system (e.g., a current-position matrix (CPM)). Processing circuit 41 estimates the position of shaft electrode 52 and electrode 55 by performing a lookup in the CPM.

[0061] Other methods of determining the position of the distal end of the catheter may be used, for example based on ultrasound transducers and receivers, using imaging techniques such as ultrasound or MRI or CT scanning (which may include placing radiopaque tags on the catheter 40).

[0062] The processing circuit 41 is typically programmed with software to perform the functions described herein. The software may be downloaded to the computer in electronic form over a network, for example, or it may alternatively or additionally be provided and / or stored on a non-transitory tangible medium such as magnetic, optical, or electronic memory.

[0063] For simplicity and clarity, Figure 1 Only the elements related to the technology disclosed in the present invention are shown. System 20 generally includes additional modules and elements that are not directly related to the technology disclosed in the present invention and thus the additional modules and elements are not directly related to the technology disclosed in the present invention. Figure 1 and the corresponding descriptions are intentionally omitted.

[0064] The catheter 40 described above includes eight flexible arms 54, wherein each arm 54 has six electrodes 55. By way of example only, any suitable catheter may be used in place of the catheter 40, for example, a catheter having a different number of flexible arms and / or electrodes on each arm, or a different probe shape such as a balloon catheter or a lasso catheter.

[0065] The medical procedure 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. The console 24 may include an RF signal generator 34 configured to generate an electrical signal that is applied by one or more electrodes of a catheter connected to the console 24 (and optionally, one or more of the surface electrodes 49) to perform electroporation or RF ablation of the myocardium of the heart 26. The 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 also include a temperature sensor (not shown) for measuring the temperature of the myocardium during RF ablation and adjusting the ablation power and / or the irrigation rate of the pumping of the irrigation fluid based on the measured temperature.

[0066] The system 20 may further include a probe 36 that is also configured for insertion into a chamber of the heart 26 and includes an electrode 38. The probe 36 may be implemented as part of the catheter 40 or as part of a different catheter. The system 20 also includes a pacing unit 46 disposed in the console 24 and configured to generate a series of pacing pulses for application to the electrode 38, as described with reference to FIG. Figures 3 to 6 Described in more detail.

[0067] Now see Figure 3 , the figure is from Figure 1 Schematic diagram of an intracardiac electrogram 60 generated by the system 20 of FIG. The intracardiac electrogram 60 has been annotated to show the timing of pacing pulses 62, which are applied to the myocardium to induce electrical activation of the myocardium, which is shown as peaks 64 of the signal. The intracardiac electrogram 60 includes two large peaks 64-1, 64-4 following the pacing pulses 62-1, 62-4, respectively. The peaks 64-1, 64-4 exceed the threshold signal amplitude 66. The peak 64-2 following the pacing pulse 62-2 is much smaller than the large peaks 64-1, 64-4 and is less than the threshold signal amplitude 66. There is no peak following the pacing pulse 62-3. Therefore, of the four pacing pulses 62, the peaks 64-1, 64-4 provided by the electrode 55 ( Figure 2 ) captures two electrical activations. Electrode 55 may be assigned a capture grade of 50%, or (2 out of 4), or "fair." Another of the electrodes may capture 4 electrical activations and may be assigned a capture grade of, for example, 100%, or (4 out of 4), or "excellent." If one electrode has a capture grade of 100%, this means that all pacing pulses were captured by the myocardium of the heart, and another electrode with a capture grade of 50% was unable to capture some of the electrical activations due to poor placement of the electrode.

[0068] Now see Figure 4 , the figure is Figure 3 Schematic diagram of a portion of an intracardiac electrogram 60 showing a peak 64-1 following a pacing pulse 62-1. Processing circuit 41 ( Figure 1 ) is configured to evaluate a given electrode 55 ( Figure 2 ) Successful acquisition of the electrical activation induced by the corresponding pacing pulse 62-1. Figure 4 The intracardiac electrogram 60 is shown to exceed a threshold signal amplitude 66 within a time window 68. The time window 68 may have any suitable value, for example, in the range of 0.04 seconds to 0.3 seconds. The threshold signal amplitude 66 may have any suitable amplitude, for example, in the range of 0.5 mV to 1.5 mV.

[0069] Now see Figure 5 , the figure is made by Figure 1 Schematic diagram of user interface 70 generated by system 20. Figure 5 The image displayed on the display 27 is shown by the electrode 55 ( Figure 2 ) are two intracardiac electrograms 60-1, 60-2 sensed by two corresponding electrodes in FIG. Next to each intracardiac electrogram 60-1, 60-2, the corresponding capture level 72 is displayed. The intracardiac electrogram 60-1 shows that two electrical activations above the threshold are captured by the corresponding electrode 55 and are therefore assigned a capture level 72 of 50%. The intracardiac electrogram 60-2 shows that four electrical activations above the threshold are captured by the electrode 55 and are therefore assigned a capture level 72 of 100%. Figure 5 Also shown is a representation of the catheter 40 within a chamber of the heart 26, with two electrodes labeled using annotation 74 showing the number assigned to each electrode.

[0070] Now see Figure 6 , the figure includes Figure 1 Flowchart 80 of the steps in the method of operating the medical procedure system 20. Figure 1 Physician 30 inserts (block 82) probe 36 into a chamber of heart 26 of a living subject (e.g., patient 28). Physician 30 also inserts (block 82) another probe (e.g., a portion of catheter 40) into the chamber. In the following description, for clarity, the other probe is referred to as catheter 40. Probe 36 can be implemented as a portion of catheter 40 or as a portion of a different catheter. In some exemplary embodiments, instead of inserting another probe, physician 30 applies one or more body surface electrodes to the tissue surface of patient 28.

[0071] The processing circuit 41 is optionally configured to track (block 84) the electrodes 55 ( Figure 2 ) in the electrode (hereinafter referred to as "electrode 55"). The processing circuit 41 may use any suitable position tracking method (e.g., the above reference Figure 1 Processing circuitry 41 may optionally track the position of electrode 55 and / or other of electrodes 38 of probe 36.

[0072] The pacing unit 46 is configured to generate (block 86) pacing pulses for application by the electrodes 38 of the probe 36. In response, the electrodes 38 are configured to apply (block 88) a sequence of pacing pulses 62 at a location in the chamber ( Figure 3) to induce a corresponding sequence of electrical activations in the myocardium of the chamber over time. The electrodes 55 of the catheter 40 (or body surface electrodes) are configured to sense (block 90) the electrical activation signals 60 ( Figure 3 The other electrodes 55 of the catheter 40 may also be configured to sense corresponding electrical activation signals in response to electrical activation induced by the capture of pacing pulses in the myocardium of the chamber over time.

[0073] The processing circuit 41 is configured to evaluate (block 92) the successful acquisition of the induced electrical activation by the electrode 55 (or body surface electrode) in response to the electrical activation signal 60. In some exemplary embodiments, the processing circuit 41 is configured to evaluate the successful acquisition of the induced electrical activation by the electrode 55 (or body surface electrode) in response to the amplitude of the electrical activation signal 60 being within a given time window 68 ( Figure 4 ) exceeds the threshold signal amplitude 66 ( Figure 4 ), evaluating the success of electrode 55 in acquiring the corresponding electrical activation induced by the corresponding pacing pulse in pacing pulse 62. The above steps can also be performed on the corresponding electrical activation signals of other corresponding electrodes in electrode 55.

[0074] The processing circuit 41 is configured to calculate (block 94) a capture level 72 ( ) for the electrode 55 (or body surface electrode) in response to the assessment of successful acquisition of the induced electrical activation by the electrode 55 (or body surface electrode). Figure 5). The capture level generally indicates a count of induced electrical activations that were assessed as being successfully acquired by the electrode 55. The steps of box 94 may be repeated for other electrodes 55 of the catheter 40. The capture level may be calculated based on the following counts: successful acquisition of electrical activations and electrical activations that were not acquired (where electrical activations are expected to occur, for example, within a time window after each pacing pulse); or the total count of successful acquisition of electrical activations and pacing pulses; or the total count of electrical activations that were not acquired and pacing pulses. Thus, the processing circuit 41 may be configured to calculate the capture level in response to the count of induced electrical activations that were assessed as being successfully acquired by the electrode 55; and the total count of electrical activations that were not acquired by the electrode 55 or were not acquired in response to a pacing pulse. In some exemplary embodiments, the processing circuit 41 is configured to calculate the capture level in response to the count of electrical activations that were not acquired and the total count of pacing pulses. The capture grade can 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 grade, for example, "very poor" if the capture grade is 20% or less, "poor" if the capture grade is greater than or equal to 20% but less than 40%, "fair" if the capture grade is greater than or equal to 40% but less than 60%, "good" if the capture grade is greater than or equal to 60% 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.

[0075] The processing circuit 41 is configured to present (block 96) the capture level 72 to the display 27 as Figure 5 In some exemplary embodiments, the processing circuit 41 is configured to present the capture level 72 with a representation of the electrical activation signal 60 to the display 27, as shown. Figure 5 In some embodiments, the processing circuit 41 is configured to present a representation of the catheter 40 to the display 27 in response to the tracked position. The corresponding capture level 72 and optionally the corresponding intracardiac electrogram 60 of the corresponding electrode 55 may be presented to the display 27. An annotation 74 ( Figure 5 ) of the catheter 40.

[0076] As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows the component or collection of elements to achieve its intended purpose as described herein. More specifically, "about" or "approximately" can refer to a value range of ±20% of the recited value, for example, "about 90%" can refer to a value range of 72% to 108%.

[0077] For clarity, various features of the invention described in the context of separate embodiments may also be provided in combination in a single exemplary embodiment. Conversely, various features of the invention described in the context of a single embodiment for simplicity may also be provided separately or in any suitable subcombination.

[0078] The above embodiments are cited by way of example, and the present invention is not limited by what has been specifically shown and described hereinabove. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A medical procedure system comprising: a first probe configured for insertion into a cardiac chamber of a living subject and comprising a first electrode configured to apply a pacing pulse sequence at a location in the chamber; a second probe comprising a second electrode configured to sense an electrical activation signal in response to electrical activation induced by capturing the pacing pulse in myocardium of the chamber over time; monitor; as well as a processing circuit, the processing circuit being configured to: configured to track the position of the second electrode; assessing successful acquisition of electrical activation induced by the second electrode pair in response to the electrical activation signal, the successful acquisition indicating successful capture of the pacing pulse by the myocardium; calculating a capture level in response to the assessment of the successful acquisition of the induced electrical activations, the capture level indicating a count of the induced electrical activations assessed as successfully acquired; as well as The capture level is presented to the display via a representation of the second probe, the representation of the second probe being presented responsive to the tracked position.

2. A system according to claim 1, wherein the processing circuit is configured to evaluate the successful acquisition of the corresponding electrical activation in the electrical activation induced by the second electrode pair by the corresponding pacing pulse in response to the electrical activation signal exceeding a threshold signal amplitude within a given time window after the corresponding pacing pulse. 3 . The system of claim 1 , wherein the processing circuit is configured to calculate the capture level in response to a count of the induced electrical activations assessed as successfully acquired by the second electrode. 4 . The system of claim 3 , wherein the processing circuit is configured to calculate the capture level also in response to counts of uncollected electrical activations.

5. The system of claim 3, wherein the processing circuit is configured to calculate the capture level further in response to a total count of the pacing pulses.

6. The system of claim 1, wherein the processing circuit is configured to calculate the capture level in response to a count of unacquired electrical activations and a total count of the pacing pulses.

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

8. The system of claim 1, wherein the processing circuit is configured to present the capture level with a representation of the electro-activation signal to the display.

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