IDENTIFICATION AND VISUALIZATION OF CARDIAC ACTIVIATION SEQUENCE IN MULTI-CHANNEL RECORDINGS
1. A method comprising:
- inserting a probe into a heart of a living subject, the probe having a plurality of electrodes;
recording respective intracardiac electrograms from the electrodes;
establishing annotations for each of the electrograms, including annotated activation times, the annotations being based on a change in voltage per unit time and defining a pattern comprising a velocity of electrical propagation in the heart;
within a time window detecting from the annotations a velocity pattern in the annotations of a set of the electrograms and the electrodes thereof;
sorting the electrograms by the annotated activation times;
sorting the electrograms by locations;
displaying the electrograms of the set, the electrograms being displayed in a graph of time-varying signal voltages; and
ablating a region of the heart based on the graph.
Intracardiac electrograms are recorded using a multi-electrode catheter and respective annotations established. Within a time window a pattern comprising a monotonically increasing local activation time sequence from a set of electrograms from neighboring electrodes is detected. The set is reordered and displayed for the operator.
- 1. A method comprising:
inserting a probe into a heart of a living subject, the probe having a plurality of electrodes; recording respective intracardiac electrograms from the electrodes; establishing annotations for each of the electrograms, including annotated activation times, the annotations being based on a change in voltage per unit time and defining a pattern comprising a velocity of electrical propagation in the heart; within a time window detecting from the annotations a velocity pattern in the annotations of a set of the electrograms and the electrodes thereof; sorting the electrograms by the annotated activation times; sorting the electrograms by locations; displaying the electrograms of the set, the electrograms being displayed in a graph of time-varying signal voltages; and ablating a region of the heart based on the graph.
- View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 18, 19, 20)
- 2. The method according to claim 2, wherein the electrograms are recorded concurrently.
- 3. The method according to claim 3, further comprising the step of sorting the set according to positions on the probe of the electrodes thereof.
- 11. An apparatus comprising:
a probe having a plurality of electrodes on a distal portion thereof; electrical circuitry for recording respective time-varying electrograms from the electrodes when the probe is adapted to be at a location in a heart of a living subject; a memory for storing the electrograms; a display; and a processor connected to the memory and operative to; record respective intracardiac electrograms from the electrodes; establish annotations for each of the electrograms, including annotated activation times, the annotations being based on a change in voltage per unit time and defining a pattern comprising a velocity of electrical propagation in the heart; within a time window detect from the annotations a velocity pattern in the annotations of a set of the electrograms and the electrodes thereof; sort the electrograms by the annotated activation times; sort the electrograms by locations; display the electrograms of the set, the electrograms being displayed in a graph of time-varying signal voltages; and ablate a region of the heart based on the graph.
- View Dependent Claims (12, 13, 14, 15, 16, 17)
This application is a continuation of U.S. patent application Ser. No. 15/179,002, filed Jun. 10, 2016, now U.S. Pat. No. 10,349,855, the entire content of which is incorporated herein by reference.
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
This invention relates to cardiac physiology. More particularly, this invention relates to the evaluation of electrical propagation in the heart.
The meanings of certain acronyms and abbreviations used herein are given in Table 1.
Cardiac arrhythmias such as atrial fibrillation are an important cause of morbidity and death. Commonly assigned U.S. Pat. No. 5,546,951, and U.S. Pat. No. 6,690,963, both issued to Ben Haim and PCT application WO 96/05768, all of which are incorporated herein by reference, disclose methods for sensing an electrical property of heart tissue, for example, local activation time, as a function of the precise location within the heart. Data are acquired with one or more catheters having electrical and location sensors in their distal tips, which are advanced into the heart. Methods of creating a map of the electrical activity of the heart based on these data are disclosed in commonly assigned U.S. Pat. No. 6,226,542, and U.S. Pat. No. 6,301,496, both issued to Reisfeld, which are incorporated herein by reference. As indicated in these patents, location and electrical activity is typically initially measured on about 10 to about 20 points on generate a preliminary reconstruction or map of the cardiac surface. The preliminary map is often combined with data taken at additional points in order to generate a more comprehensive map of the heart'"'"'s electrical activity. Indeed, in clinical settings, it is not uncommon to accumulate data at 100 or more sites to generate a detailed, comprehensive map of heart chamber electrical activity. The generated detailed map may then serve as the basis for deciding on a therapeutic course of action, for example, tissue ablation, to alter the propagation of the heart'"'"'s electrical activity and to restore normal heart rhythm.
Catheters containing position sensors may be used to determine the trajectory of points on the cardiac surface. These trajectories may be used to infer motion characteristics such as the contractility of the tissue. As disclosed in U.S. Pat. No. 5,738,096, issued to Ben Haim, which is incorporated herein in its entirety by reference, maps depicting such motion characteristics may be constructed when the trajectory information is sampled at a sufficient number of points in the heart.
Electrical activity at a point in the heart is typically measured by advancing a multiple-electrode catheter to measure electrical activity at multiple points in the heart chamber simultaneously. A record derived from time varying electrical potentials as measured by one or more electrodes is known as an electrogram. Electrograms may be measured by unipolar or bipolar leads, and are used, e.g., to determine onset of electrical propagation at a point, known as local activation time.
However, determination of local activation time as an indicator of electrical propagation becomes problematic in the presence of conduction abnormalities. For example, atrial electrograms during sustained atrial fibrillation have three distinct patterns: single potential, double potential and complex fractionated atrial electrograms. Thus, compared to a normal sinus rhythm signal, an atrial fibrillation signal is extremely complex, as well as being more variable. While there is noise on both types of signal, which makes analysis of them difficult, because of the complexity and variability of the atrial fibrillation signal the analysis is correspondingly more difficult. On the other hand, in order to overcome the atrial fibrillation in a medical procedure, it is useful to establish possible paths of activation waves travelling through the heart representing atrial fibrillation. Once these paths have been identified, they may be blocked, for example, by appropriate ablation of a region of the heart. The paths may be determined by analysis of intra-cardiac atrial fibrillation signals, and embodiments of the present invention facilitate the analysis.
A typical multi-electrode catheter, such as the Pentaray® NAV catheter, has on its distal end numerous electrodes (approximately 60 or more), which acquire respective sets of ECG signals from different points in the heart. These electrodes are distributed over the splines. The signals may be presented as individual graphs of time-varying signal voltages. Conventionally, the order of presentation of these graphs is according to the electrode position on the splines. In such displays of multielectrode catheter recordings, it is difficult to follow the activation sequence in different electrodes. Therefore it is not easy to identify the existence of reentrant activation pathways or their location.
Embodiments of the present invention simultaneously acquire electropotential signals in the heart using a catheter having a multiplicity of electrodes at its distal end, each electrode generating a respective unipolar signal. The signals may be considered as unipolar signals, or in combination with another electrode, as bipolar signals. Each of the ECG signals are annotated to find the local activation time (LAT) and displayed as time-varying voltages. The graphs are then further analyzed to detect relationships in the LATs obtained from neighboring points in the heart, for example a monotonic increase in LAT. If a pattern is found, the graphs are reordered to include a new group whose members present the pattern. By analyzing the reordered graphs over time, mutations in conduction patterns at neighboring locations can conveniently be detected.
There is provided according to embodiments of the invention a method which is carried out by inserting a multi-electrode probe into a heart of a living subject, recording respective intracardiac electrograms from the electrodes, establishing respective annotations for the electrograms, and within a time window detecting from the annotations a velocity pattern comprising a monotonically increasing local activation time sequence in a set of the electrograms and the electrodes thereof, wherein each electrode of the set is disposed within a predetermined distance from at least one other electrode of the set, and displaying the electrograms of the set.
According to another aspect of the method, the electrograms are recorded concurrently.
A further aspect of the method includes sorting the set according to positions on the probe of the electrodes thereof.
According to yet another aspect of the method, the pattern can be a reentrant activation circuit, a micro reentry pattern, a focal source pattern, and a macro reentry pattern.
According to one aspect of the method, displaying the electrograms of the set includes sorting the set according to local activation times thereof.
Still another aspect of the method is carried out in a new time window by detecting a change in the pattern, and responsively to the change, iterating sorting the set and displaying the electrograms.
According to an additional aspect of the method, the change includes a change in a direction of electrical propagation.
According to one aspect of the method, the change includes a change in a speed of electrical propagation.
There is further provided according to embodiments of the invention an apparatus including a probe having a plurality of electrodes on a distal portion thereof, electrical circuitry for recording respective time-varying electrograms from the electrodes when the probe is at a location in a heart of a living subject, a memory for storing the electrograms, a display, and a processor connected to the memory. The processor is operative for establishing annotations of local activation times from the respective intracardiac electrograms, defining a pattern from the annotations that includes a velocity of electrical propagation in the heart, within a time window detecting a monotonically increasing local activation time sequence pattern in the annotations of a set of the electrograms and the electrodes thereof, each electrode of the set being disposed within a predetermined distance from at least one other electrode of the set, and displaying the electrograms of the set on the display.
For a better understanding of the present invention, reference is made to the detailed description of the invention, by way of example, which is to be read in conjunction with the following drawings, wherein like elements are given like reference numerals, and wherein:
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the various principles of the present invention. It will be apparent to one skilled in the art, however, that not all these details are necessarily needed for practicing the present invention. In this instance, well-known circuits, control logic, and the details of computer program instructions for conventional algorithms and processes have not been shown in detail in order not to obscure the general concepts unnecessarily.
Documents incorporated by reference herein are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.
Annotations” or “annotation points” refer to points or candidates on an electrogram that are considered to denote events of interest. In this disclosure the events are typically onset (local activation time) of the propagation of an electrical wave as sensed by the electrode.
For purposes of this disclosure two electrodes are proximate or “close to” each other, when either they are within 15 mm of one another on the catheter, or they are nearest to one another among other electrodes in space or in position on the catheter, e.g., succeeding one another in position on a ray of a spline catheter or a spine of a basket catheter. Two electrodes may also be “close to” one another if they are on corresponding or succeeding positions of two spines or rays that are not separated by intervening spines or rays.
Turning now to the drawings, reference is initially made to
The system 10 may comprise a general purpose or embedded computer processor, which is programmed with suitable software for carrying out the functions described hereinbelow. Thus, although portions of the system 10 shown in other drawing figures herein are shown as comprising a number of separate functional blocks, these blocks are not necessarily separate physical entities, but rather may represent, for example, different computing tasks or data objects stored in a memory that is accessible to the processor. These tasks may be carried out in software running on a single processor, or on multiple processors. The software may be provided to the processor or processors on tangible non-transitory media, such as CD-ROM or non-volatile memory. Alternatively or additionally, the system 10 may comprise a digital signal processor or hard-wired logic. One commercial product embodying elements of the system 10 is available as the CARTO® 3 System, available from Biosense Webster, Inc., 3333 Diamond Canyon Road, Diamond Bar, Calif. 91765. This system may be modified by those skilled in the art to embody the principles of the invention described herein.
Areas determined to be abnormal, for example by evaluation of the electrical activation maps, can be ablated by application of thermal energy, e.g., by passage of radiofrequency electrical current through wires in the catheter to one or more electrodes at the distal tip 18, which apply the radiofrequency energy to the myocardium. The energy is absorbed in the tissue, heating it to a point (typically about 50° C.) at which it permanently loses its electrical excitability. When successful, this procedure creates non-conducting lesions in the cardiac tissue, which disrupt the abnormal electrical pathway causing the arrhythmia. The principles of the invention can be applied to different heart chambers to diagnose and treat many different cardiac arrhythmias.
The catheter 14 typically comprises a handle 20, having suitable controls on the handle to enable the operator 16 to steer, position and orient the distal end of the catheter as desired for the ablation. To aid the operator 16, the distal portion of the catheter 14 contains position sensors (not shown) that provide signals to a processor 22, located in a console 24. The processor 22 may fulfill several processing functions as described below.
The catheter 14 is a multi-electrode catheter, which can be a basket catheter as shown in the right portion of the balloon or a spline catheter as shown in the left portion. In any case there are multiple electrodes 32, which are used as sensing electrodes and have known locations on the basket or spline, and known relationships to one another. Thus, once the catheter is located in the heart, for example by constructing a current position map, the location of each of the electrodes 32 in the heart is known. One method for generation of a current position map is described in commonly assigned U.S. Pat. No. 8,478,383 to Bar-Tal et al., which is herein incorporated by reference.
Electrical signals can be conveyed to and from the heart 12 from the electrodes 32 located at or near the distal tip 18 of the catheter 14 via cable 34 to the console 24. Pacing signals and other control signals may be conveyed from the console 24 through the cable 34 and the electrodes 32 to the heart 12.
Wire connections 35 link the console 24 with body surface electrodes 30 and other components of a positioning sub-system for measuring location and orientation coordinates of the catheter 14. The processor 22, or another processor (not shown) may be an element of the positioning subsystem. The electrodes 32 and the body surface electrodes 30 may be used to measure tissue impedance at the ablation site as taught in U.S. Pat. No. 7,536,218, issued to Govari et al., which is herein incorporated by reference. A temperature sensor (not shown), typically a thermocouple or thermistor, may be mounted near the distal tip 18 of the catheter 14.
The console 24 typically contains one or more ablation power generators 25. The catheter 14 may be adapted to conduct ablative energy to the heart using any known ablation technique, e.g., radiofrequency energy, ultrasound energy, and laser-produced light energy. Such methods are disclosed in commonly assigned U.S. Pat. Nos. 6,814,733, 6,997,924, and 7,156,816, which are herein incorporated by reference.
In one embodiment, the positioning subsystem comprises a magnetic position tracking arrangement that determines the position and orientation of the catheter 14 by generating magnetic fields in a predefined working volume and sensing these fields at the catheter, using field generating coils 28. The positioning subsystem U.S. Pat. No. 7,756,576, which is hereby incorporated by reference, and in the above-noted U.S. Pat. No. 7,536,218.
As noted above, the catheter 14 is coupled to the console 24, which enables the operator 16 to observe and regulate the functions of the catheter 14. Console 24 includes a processor, preferably a computer with appropriate signal processing circuits. The processor is coupled to drive a monitor 29. The signal processing circuits typically receive, amplify, filter and digitize signals from the catheter 14, including signals generated by the above-noted sensors and a plurality of location sensing electrodes (not shown) located distally in the catheter 14. The digitized signals are received and used by the console 24 and the positioning system to compute the position and orientation of the catheter 14 and to analyze the electrical signals from the electrodes as described in further detail below.
Typically, the system 10 includes other elements, which are not shown in the figures for the sake of simplicity. For example, the system 10 may include an electrocardiogram (ECG) monitor, coupled to receive signals from one or more body surface electrodes, so as to provide an ECG synchronization signal to the console 24. As mentioned above, the system 10 typically also includes a reference position sensor, either on an externally-applied reference patch attached to the exterior of the subject'"'"'s body, or on an internally-placed catheter, which is inserted into the heart 12 maintained in a fixed position relative to the heart 12. The system 10 may receive image data from an external imaging modality, such as an MRI unit or the like and includes image processors that can be incorporated in or invoked by the processor 22 for generating and displaying images that are described below.
Reference is now made to
Those skilled in the art will also appreciate that a process could alternatively be represented as a number of interrelated states or events, e.g., in a state diagram. Moreover, not all illustrated process steps may be required to implement the method.
At initial step 39 a chamber of the heart is catheterized conventionally with a multi-electrode catheter. Either a multi-spline catheter of a basket catheter is suitable. In such catheters each electrode has a known position on the basket or the splines as the case may be. Once the catheter is in place, if desired a current position map may be constructed using location sensors in the catheter, for example magnetic location sensors or using impedance measurements as noted above. The location of each of the electrodes in the heart is known from the current position map, or can be determined using imaging techniques. A typical multi-spline catheter used with the CARTO 3 system has, on its distal end, 60 electrodes, which acquire 60 sets of ECG signals from 60 points in the heart. The electrodes are distributed over the splines, assumed herein to be eight splines. The signals may be presented as 60 voltage vs time graphs. The order of presentation of the 60 graphs is typically according to the electrode position on the splines. While exemplified by the discussion of
Next, at step 41 intracardiac electrograms are recorded concurrently from of the electrodes in respective channels. The recordings are annotated, for example by determining time windows in which there is a maximal change in voltage, i.e., a maximum value of |dv/dt|. In cases of conduction abnormalities where electrical propagation is more complex, annotation may be accomplished using the teachings of commonly assigned U.S. Patent Application Publication No. 20150208942, entitled Double Bipolar Configuration for Atrial Fibrillation Annotation by Bar-Tal et al., whose disclosure is herein incorporated by reference.
In order to better illustrate the difficulties that can be solved by application of the principles of the invention, reference is now made to
Continuing to refer to
Next, in step 52 the groups of electrograms are sorted again, now according to location of the electrodes. Sorting can be done according to location of electrodes on the catheter, first along the spline and then between adjacent splines. Alternatively, electrodes may be grouped according to location in the heart and the groups sorted by proximity.
Reference is now made to
The benefits of sorting groups of electrograms are described below with reference to
Reference is now made to
Reference is now made to
Another effect of ordering the electrograms by location is shown in
Another pattern revealed by ordering the electrograms by location is shown in
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.