Electro-anatomical mapping and annotation presented in electrophysiological procedures
A catheter includes: (a) a shaft for insertion into a heart of a patient, (b) an expandable distal-end assembly, which is coupled to the shaft and is configured to make contact with tissue of the heart, (c) at least first and second electrocardiogram (ECG) electrodes, which are coupled to an outer surface of the expandable distal-end assembly, and when placed in contact with the tissue, are configured to sense ECG signals in the tissue, and (d) a reference electrode, which is positioned within an inner volume of the distal-end assembly, and in an expanded position of the distal-end assembly, the reference electrode: (i) has no physical contact with the tissue, and (ii) is positioned at a first distance from the first ECG electrode and at a second distance from the second ECG electrode, and the difference between the first and second distances is smaller than a predefined threshold.
1. A catheter system, comprising:
a shaft for insertion into a heart of a patient;
an expandable distal-end assembly, which is coupled to the shaft and is configured to make contact with tissue of the heart;
at least first and second electrocardiogram (ECG) electrodes, which are coupled to an outer surface of the expandable distal-end assembly, and, when placed in contact with the tissue, are configured to sense ECG signals in the tissue;
a reference electrode, which is positioned within an inner volume of the expandable distal-end assembly, and wherein in an expanded position of the expandable distal-end assembly, the reference electrode: (i) has no physical contact with the tissue, and (ii) is positioned at a first distance from the first ECG electrode and at a second distance from the second ECG electrode, wherein a difference between the first and second distances is smaller than a predefined threshold; and
a processor configured to:
calculate, based on the ECG signals sensed at one or more positions on the tissue, one or more respective local activation times (LATs), which are indicative of an electrophysiological wave propagating in the tissue;
identify, based at least in part on the calculated LATs, a timing error of a rhythm of the heart; and
output for display an annotation over a graph of at least one of the ECG signals, the annotation being indicative of the timing error identified in the rhythm of the heart.
2. The catheter system according to claim 1 , wherein the expandable distal-end assembly comprises at least first and second splines, and wherein the first and second ECG electrodes are coupled to the first and second splines, respectively.
3. The catheter system according to claim 1 , wherein in the expanded position, the reference electrode is positioned at least 9 mm from the tissue.
4. The catheter system according to claim 1 , wherein at least one of the ECG signals comprises a unipolar ECG signal, which is sensed in the tissue relative to the reference electrode.
5. The catheter system according to claim 1 , wherein the processor is configured to display at least the annotation in a bar graph.
6. The catheter system according to claim 5 , wherein the processor is configured to display in the bar graph at least a first annotation indicative of a first type of the timing error, and a second different annotation, which is indicative of a second type of the timing error, different from the first type.
7. The catheter system according to claim 1 , wherein the reference electrode is disposed on the shaft.
8. The catheter system according to claim 1 , wherein the reference electrode is further configured as a reference electrode for applying a unipolar ablation signal between one or more ablation electrodes disposed on the expandable distal-end assembly and the reference electrode.
9. A method, comprising:
inserting, into a heart of a patient, an expandable distal-end assembly having an expanded position for making contact with tissue of the heart, the expandable distal-end assembly comprising: (i) at least first and second electrocardiogram (ECG) electrodes, which are coupled to an outer surface of the expandable distal-end assembly for sensing ECG signals with the tissue when placed in contact with the tissue, and (ii) a reference electrode, which is positioned within an inner volume of the expandable distal-end assembly, and in the expanded position: (a) has no physical contact with the tissue, and (b) is positioned at a first distance from the first ECG electrode and at a second distance from the second ECG electrode, wherein a difference between the first and second distances is smaller than a predefined threshold;
expanding the expandable distal-end assembly for placing at least the first and second ECG electrodes in contact with the tissue;
sensing ECG signals in the tissue using at least the first and second ECG electrodes;
calculating, based on the ECG signals sensed at one or more positions on the tissue, one or more respective local activation times (LATs), which are indicative of an electrophysiological wave propagating in the tissue;
identifying, based at least in part on the calculated LATs, a timing error of a rhythm of the heart; and
outputting for display an annotation over a graph of at least one of the ECG signals, the annotation being indicative of the timing error identified in the rhythm of the heart.
10. The method according to claim 9 , wherein the expandable distal-end assembly comprises at least first and second splines, and wherein the first and second ECG electrodes are coupled to the first and second splines, respectively.
11. The method according to claim 9 , wherein expanding the expandable distal-end assembly comprises positioning the reference electrode at least 9 mm from the tissue.
12. The method according to claim 9 , wherein sensing the ECG signals comprises sensing in the tissue a unipolar ECG signal relative to the reference electrode.
13. The method according to claim 9 , wherein displaying at least the annotation comprises displaying at least the annotation in a bar graph.
14. The method according to claim 13 , wherein displaying at least the annotation in the bar graph comprises displaying in the bar graph, at least a first annotation indicative of a first type of the timing error, and a second different annotation, which is indicative of a second type of the timing error, different from the first type.