Electrode Contact Indication

Abstract

To provide a medical system.SOLUTION: In one embodiment, a medical system 20 includes: a catheter 40 to be inserted into a chamber of a heart 26 of a living subject 28, the catheter including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart 26; a display 27; and processing circuitry 41 to receive signals from the catheter and, in response to the signals, assess the quality of contact of each of the catheter electrodes with the tissue in the heart, and render to the display 27 respective intracardiac electrogram traces representing electrical activity in the tissue that is sensed by the catheter electrodes at the respective locations, while modifying a visual feature of at least some of the traces responsively to the quality of contact of the catheter electrodes with the tissue of the heart 26 at the respective locations.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to medical systems, particularly but not exclusively to catheter-based systems. [Background technology]

[0002] A wide range of medical procedures involve the placement of probes, such as catheters, within a patient's body. To track such probes, position sensing systems have been developed. 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 the signals are processed to determine the position coordinates 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, the disclosures of which are incorporated herein by reference in their entireties. Position may be tracked using an impedance-based system or a current-based system.

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

[0004] The diagnosis and treatment of cardiac arrhythmias involves mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volume, and selectively ablating cardiac tissue by application of energy. Such ablation can stop or modify the propagation of undesired electrical signals from one part of the heart to another. Ablation techniques destroy undesired electrical pathways by creating non-conductive lesions. Various modes of energy delivery have been previously disclosed for creating lesions, including the use of microwave, laser, and more generally radio frequency energy to create conduction blockages along cardiac tissue walls. In a two-step mapping-then-ablation procedure, a catheter equipped with one or more electrical sensors is typically advanced into the heart to sense and measure electrical activity at each point in the heart by acquiring data at multiple points. These data are then used to select a target area in the heart where the ablation should be performed.

[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 and to ablate sites of abnormal electrical activity. In use, the electrode catheter is inserted into a major vein or an artery, such as the femoral artery, and then guided into the chamber of the heart to be targeted. A typical ablation procedure involves inserting a catheter with one or more electrodes at its distal end into a heart chamber. A reference electrode may be provided by a second catheter, which is typically taped to the patient's skin or placed in or near the heart. When a radio frequency (RF) current is applied to the tip electrode of the ablation catheter, the current flows in the medium surrounding the tip electrode, i.e., blood and tissue, toward the reference electrode. The distribution of the current is determined by the amount of the electrode surface that is in contact with the tissue, which has a higher electrical conductivity compared to blood. Heating of the tissue occurs due to the electrical resistance of the tissue. If the tissue is heated sufficiently, the cells of the cardiac tissue are destroyed, forming a non-conductive lesion in the cardiac tissue.

[0006] Thus, when an ablation catheter or other catheter is placed within the body, particularly near endocardial tissue, it is desirable to have the distal tip of the catheter in direct contact with the tissue. This contact can be verified, for example, by measuring contact between the distal tip and the body tissue. U.S. Patent Application Publication Nos. 2007 / 0100332, 2009 / 0093806, and 2009 / 0138007, the disclosures of which are incorporated herein by reference, describe methods of sensing contact pressure between the distal tip of a catheter and tissue within a body cavity using a force sensor embedded within the catheter.

[0007] Several references, including U.S. Patent Nos. 5,935,079, 5,891,095, 5,836,990, 5,836,874, 5,673,704, 5,662,108, 5,469,857, 5,447,529, 5,341,807, 5,078,714, and Canadian Patent Application No. 2,285,342, report methods for determining electrode-tissue contact. Some of these references, such as U.S. Patent Nos. 5,935,079, 5,836,990, and 5,447,529, determine electrode-tissue contact by measuring the impedance between the tip and return electrodes. As disclosed in the '529 patent, it is known that the impedance through blood is generally lower than the impedance through tissue, and therefore tissue contact is detected by comparing the impedance value across a set of electrodes to previously measured impedance values ​​when one electrode is known to be in contact with tissue and when one electrode is known to be in contact with blood only.

[0008] U.S. Patent No. 9,168,004 to Gliner et al., incorporated herein by reference, describes using machine learning to determine catheter electrode contact. The '004 patent describes a cardiac catheterization procedure performed by storing an indication of the contact state between an electrode of the probe and the wall of the heart as in contact or not in contact, making a series of determinations of the impedance phase angle of the current through this electrode and another electrode, identifying the maximum and minimum phase angles in the series of determinations, and defining a binary classifier as the midpoint between the extremes. The test value is compared to the classifier as adjusted by a hysteresis coefficient, and a change in the set state is reported if the test value is greater than or less than the adjusted classifier.

[0009] U.S. Patent Application Publication No. 2013 / 0085416 to Mest, incorporated herein by reference, describes a method for in vivo recalibration of a force sensing probe, such as an electrophysiology catheter, that provides for the creation of an automatic zero point zone. The distal tip of a catheter or other probe is placed within a patient's body cavity. Verification of the absence of tissue contact is made using electrocardiogram (ECG) or impedance data, fluoroscopic imaging or other real-time imaging data, and / or an electroanatomical mapping system. Once the absence of tissue contact is verified, the system recalibrates the signal emitted by the force sensor by setting it to correspond to a zero gram force reading, and this recalibrated baseline reading is used to generate and display a force reading based on the force sensor data. Summary of the Invention [Means for solving the problem]

[0010] According to one embodiment of the present disclosure, a medical system is provided that includes a catheter configured to be inserted into a chamber of a heart of a living subject, the catheter including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; a display; and a processing circuit configured to receive signals from the catheter and, in response to the signals, evaluate a respective quality of contact of each of the catheter electrodes with tissue within the heart and render on the display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each location, while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the cardiac tissue at each location.

[0011] Further, according to one embodiment of the present disclosure, the processing circuitry is configured to increase the intensity of at least some of the traces in response to respective qualities of contact of the catheter electrodes with the cardiac tissue at each location.

[0012] Furthermore, according to an embodiment of the present disclosure, the processing circuitry is configured to increase an intensity of a trace representing electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with tissue compared to a trace representing electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with tissue.

[0013] Additionally, according to one embodiment of the present disclosure, the processing circuitry is configured to change the color of at least some of the traces in response to a respective quality of contact of the catheter electrodes with the cardiac tissue at each location.

[0014] Furthermore, according to one embodiment of the present disclosure, the processing circuitry is configured to change a color of a trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with tissue compared to a trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with tissue.

[0015] Further, according to an embodiment of the present disclosure, the processing circuitry is configured to modify visual characteristics of at least some of the traces representing electrical activity sensed by those of the catheter electrodes that have a contact quality with tissue above a predetermined threshold contact quality.

[0016] Further, according to one embodiment of the present disclosure, the processing circuitry is configured to perform a first modification of a visual feature of one of the traces representing the electrical activity sensed by one of the catheter electrodes having a tissue contact quality higher than a predetermined threshold contact quality during a first time period, and to perform a second modification of the visual feature of the trace representing the electrical activity sensed by the catheter electrode having a tissue contact quality lower than the predetermined threshold contact quality during a second time period following the first time period.

[0017] Additionally, according to one embodiment of the present disclosure, the second modification of the visual characteristic varies over a second period of time.

[0018] Furthermore, according to one embodiment of the present disclosure, the second modification of the visual characteristic includes the visual characteristic darkening over a second time period.

[0019] Further, in accordance with one embodiment of the present disclosure, the system includes body surface electrodes configured to be affixed to a skin surface of a living subject, and processing circuitry configured to measure an indication of electrical impedance between the body surface electrodes and the catheter electrodes and to calculate position coordinates of the catheter electrodes in response to the indication of electrical impedance.

[0020] Further, in accordance with an embodiment of the present disclosure, the processing circuitry is configured to assess a quality of contact of each of the catheter electrodes with tissue within the heart in response to the indication of electrical impedance.

[0021] Also, in accordance with another embodiment of the present disclosure, there is provided a medical method comprising: receiving a signal from a catheter configured to be inserted into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; evaluating a respective quality of contact of each of the catheter electrodes with tissue within the heart in response to the signal; and rendering on a display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each location while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the cardiac tissue at each location.

[0022] Additionally, according to one embodiment of the present disclosure, the method includes increasing the intensity of at least some of the traces in response to a respective quality of contact of the catheter electrodes with the cardiac tissue at each location.

[0023] Furthermore, according to one embodiment of the present disclosure, increasing includes increasing a brightness of a trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with tissue compared to a trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with tissue.

[0024] Furthermore, in accordance with an embodiment of the present disclosure, the method includes changing the color of at least some of the traces in response to a respective quality of contact of the catheter electrodes with the cardiac tissue at each location.

[0025] Moreover, according to one embodiment of the present disclosure, the varying includes changing a color of a trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with tissue compared to a trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with tissue.

[0026] Additionally, according to one embodiment of the present disclosure, the modifying includes modifying visual characteristics of at least some of the traces representing electrical activity sensed by those of the catheter electrodes having a contact quality with tissue above a predetermined threshold contact quality.

[0027] Further, in accordance with one embodiment of the present disclosure, the method includes performing a first modification of a visual feature of one of the traces representing electrical activity sensed by one of the catheter electrodes having a tissue contact quality higher than a predetermined threshold contact quality during a first time, and performing a second modification of the visual feature of the trace representing electrical activity sensed by the catheter electrode having a tissue contact quality lower than the predetermined threshold contact quality during a second time following the first time.

[0028] Furthermore, according to one embodiment of the present disclosure, the second modification of the visual characteristic varies over a second period of time.

[0029] Furthermore, according to one embodiment of the present disclosure, the second modification of the visual characteristic includes the visual characteristic darkening over a second time period.

[0030] Further, in accordance with an embodiment of the present disclosure, the method includes measuring an indication of electrical impedance between a body surface electrode configured to be affixed to a skin surface of a living subject and a catheter electrode, and calculating position coordinates of the catheter electrode in response to the indication of electrical impedance.

[0031] Furthermore, in accordance with an embodiment of the present disclosure, the evaluating includes evaluating a quality of each of the catheter electrodes' contact with tissue within the heart in response to the indication of electrical impedance.

[0032] According to yet another embodiment of the present disclosure, there is provided a software product including a non-transitory computer readable medium having program instructions stored thereon, which when read by a central processing unit (CPU) cause the CPU to receive signals from a catheter configured to be inserted into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart, and in response to the signals, to evaluate a respective quality of contact of each of the catheter electrodes with tissue within the heart, and to render on a display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each location, while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the cardiac tissue at each location. [Brief description of the drawings]

[0033] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a schematic diagram of a medical treatment system constructed and operative in accordance with an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic diagram of a catheter for use in the system of FIG. 1. [Diagram 3] 2 is a flow chart including exemplary steps in a method of operation of the system of FIG. 1. [Figure 4] 2 is a flow chart including exemplary steps in a method of operation of the system of FIG. 1 utilizing electrical impedance. [Diagram 5] 2 is a schematic diagram of a first exemplary intracardiac electrogram (IEGM) tracing produced by the system of FIG. 1; [Figure 6]2 is a schematic diagram of a second exemplary intracardiac electrogram (IEGM) tracing produced by the system of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Overview As previously mentioned, in a two-step mapping-then-ablation procedure, a catheter with one or more electrodes is typically advanced into the heart to sense and measure electrical activity at each point within the heart by acquiring data at multiple points, which are then used to select a target region where ablation will be performed.

[0035] In particular, the electrical activity is usually displayed as an intracardiac electrogram (IEGM) trace that is analyzed by a physician to find the cause of the arrhythmia. Catheter electrodes that are not in contact with tissue within the heart typically measure some electrical and far-field signals from the cardiac tissue. When the catheter electrodes are in contact with the cardiac tissue, the signal amplitude is mainly based on the tissue conductivity and the far-field is small. Therefore, physicians typically focus on analyzing the IEGM traces of electrodes in contact with the tissue.

[0036] For focal catheters with one or more electrodes, typically one IEGM trace is displayed for analysis by the physician. The physician can quickly determine whether the catheter electrode supplying the signal is in contact with tissue or not based on the signal morphology. However, multi-electrode catheters that simultaneously capture electrical activity from various tissue locations may simultaneously display data from multiple IEGM traces on a single display. In some cases, the number of IEGM traces may be so large that the physician cannot easily determine which IEGM traces are supplied by electrodes in contact with tissue and which are not.

[0037] One example of a multi-electrode catheter is the Octaray® catheter, which includes 48 or more electrodes, manufactured by Biosense Webster Inc., Irvine, Calif. The Octaray includes eight deflectable arms located at the distal end of the shaft, each of which includes six electrodes. Some catheters may include many more electrodes, such as, but not limited to, 120 electrodes.

[0038] In addition to the need to determine electrode contact during mapping as described above, effective ablation generally requires sufficient contact between the ablation electrode and the tissue, so the physician performing the ablation procedure monitors the electrode-tissue contact. When the number of electrodes is small, contact monitoring can be done by a numerical or graphical display of the degree of contact, such as the impedance observed at the electrode or the force applied to the electrode. However, as the number of active electrodes used in an ablation procedure increases, it becomes increasingly difficult for the physician to monitor the parameters of each individual electrode. In the case of electrode contact, this problem is exacerbated by the fact that in most cases the parameters that measure contact change as the contact changes.

[0039] An embodiment of the present invention solves the above-mentioned problems during a medical procedure, such as a mapping or ablation procedure, by presenting a physician with multiple IEGM traces (e.g., voltage versus time graphs) of signals acquired by electrodes of a catheter, while modifying the visual characteristics of the traces that represent the electrical activity sensed by electrodes that are deemed to be in sufficient contact with the cardiac tissue. Thus, traces of electrodes with sufficient tissue contact are highlighted and can be easily identified by the physician.

[0040] Traces representing electrical activity sensed by electrodes in sufficient contact with cardiac tissue are typically altered to be brighter compared to traces representing electrical activity sensed by electrodes not in sufficient contact with cardiac tissue. The human eye is very sensitive to changes in luminance. Thus, brighter traces allow for more rapid identification of relevant IEGM traces by the physician.

[0041] In some embodiments, traces representing electrical activity sensed by electrodes in good contact with cardiac tissue are altered, typically to be a different color, as compared to traces representing electrical activity sensed by electrodes not in good contact with cardiac tissue.

[0042] In other embodiments, traces representing electrical activity sensed by electrodes in good contact with cardiac tissue are altered, typically to be a different color and brighter, as compared to traces representing electrical activity sensed by electrodes not in good contact with cardiac tissue.

[0043] A physician can then examine the highlighted signals and analyze them to detect arrhythmias and / or determine which electrodes are in contact with tissue for ablation purposes.

[0044] Non-highlighted traces indicate electrodes with poor tissue contact and the physician can use this indication to adjust the catheter position to improve tissue contact for the electrodes associated with the non-highlighted traces.

[0045] In some embodiments, a fading effect is used to dim the brightness or color used to highlight a trace associated with an electrode in good contact with tissue back to the original brightness and / or color (used for traces associated with electrodes in poor tissue contact) after the electrode associated with that trace is no longer in good contact with tissue. The fading effect may occur over any suitable time frame, such as, but not limited to, 1 to 3 seconds. The fading effect helps to smooth out brightness and / or color changes that occur due to intermittent contact and / or changes in contact quality.

[0046] In the above discussion, sufficiency of tissue contact is used to determine whether to highlight an IEGM trace. The quality of contact may be assessed based on a variety of methods, including impedance measurements, force or pressure measurements, or analysis of the IEGM trace, as described in more detail below.

[0047] The processing circuitry evaluates a respective quality of contact of each of the catheter electrodes with tissue in the heart in response to the signal provided by the catheter. Any one of the catheter electrodes may be in full or partial contact with tissue of the heart. In some cases, any one of the catheter electrodes may be in contact with tissue through another liquid, such as blood of various concentrations. The quality of contact (full or partial contact, or contact through another liquid) of any one of the catheter electrodes with tissue can be evaluated based on the signal provided by the catheter.

[0048] The term "contact quality" as used in the specification and claims is defined herein as a quantitative measure of the degree of electrical contact between one of the catheter electrodes and the tissue. As described in more detail below, "contact quality" can be expressed directly, for example using measured electrical impedance, or indirectly, for example using contact force, pressure, or IEGM amplitude.

[0049] In some embodiments, the catheter may provide a signal indicative of the impedance between the catheter electrodes and the body surface electrodes. The impedance indication represents a quality of contact, with a higher value of impedance between one of the catheter electrodes and the body surface electrode indicating a higher quality of contact between that catheter electrode and the tissue. The impedance value may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes and the tissue.

[0050] In some embodiments, the impedance between one of the catheter electrodes on the catheter and another of these catheter electrodes may be used as a measure of the quality of contact. As disclosed in the '529 patent mentioned in the background section above, it is known that the impedance through blood is generally lower than the impedance through tissue. Thus, tissue contact can be assessed by comparing the impedance value of the entire set of electrodes to previously measured impedance values ​​when one electrode is known to be in good contact with tissue and when one electrode is known to be in contact only with blood.

[0051] In some embodiments, the methods of US Pat. No. 9,168,004 to Gliner et al., incorporated herein by reference, may be used to assess contact quality using machine learning based methods.

[0052] In some embodiments, the catheter may provide a signal from a force or pressure sensor. The force or pressure indication represents the quality of contact, with higher force or pressure values ​​indicating higher quality of contact between the catheter electrodes and the tissue. The force or pressure value may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes and the tissue.

[0053] In some embodiments, the generated IEGM traces may be used to assess the quality of contact between any one of the catheter electrodes and the tissue. The maximum amplitude of the IEGM trace associated with one of the catheter electrodes indicates the quality of contact between that catheter electrode and the tissue, with a larger value of the maximum amplitude of the IEGM trace indicating a higher quality of contact between that catheter electrode and the tissue. The value of the amplitude of the IEGM trace may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes and the tissue.

[0054] System Description Documents incorporated herein by reference are to be considered as integral parts of this application and, unless any term is defined in those incorporated documents to the contrary, either expressly or impliedly, to the definition given herein, only the definition given herein is to be considered.

[0055] Reference is now made to Figure 1, which is a schematic diagram of a medical procedure system 20 constructed and operative in accordance with an embodiment of the present invention. See also Figure 2, which is a schematic diagram of a catheter 40 for use in the system 20 of Figure 1.

[0056] The medical procedure 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 includes a shaft 22 and a plurality of deflectable arms 54 (only some of which are labeled for simplicity) for insertion into a body portion of a living subject. The deflectable arms 54 have respective proximal ends connected to a distal end of the shaft 22.

[0057] The catheter 40 includes a position sensor 53 disposed on the shaft 22 in a predetermined spatial relationship 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 biaxial or triaxial coil arrangement, for providing position and orientation position data, including rotation. The catheter 40 includes a plurality of 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 in a heart of a living subject using the electrodes 55, or to perform any other suitable function within a body part of a living subject.

[0058] The medical procedure system 20 may determine the position and orientation of the shaft 22 of the catheter 40 based on signals provided by a magnetic sensor 50 attached to the shaft 22 and / or shaft electrodes 52 (proximal electrode 52a and distal electrode 52b) on either side of the magnetic sensor 50. The proximal electrode 52a, the distal electrode 52b, the magnetic sensor 50, and at least some of the electrodes 55 are connected to various driver circuits in the console 24 via the catheter connector 35 by wires extending through the shaft 22. In some 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 the driver circuits of the console 24 via the catheter connector 35. In some embodiments, the distal electrode 52b and / or the proximal electrode 52a may be omitted.

[0059] The diagram shown in Figure 2 has been selected solely for purposes of conceptual clarity. Other configurations of shaft electrode 52 and electrode 55 are possible. Additional functionality may be included in position sensor 53. For clarity, elements not relevant to the disclosed embodiment of the invention, such as irrigation ports, have been omitted.

[0060] The physician 30 navigates the catheter 40 to a target location within a body part (e.g., the heart 26) of the patient 28 by manipulating the shaft 22 using a manipulator 32 near the proximal end of the catheter 40 and / or by deflection 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 withdrawn from the sheath 23 can the deflectable arms 54 unfold and resume their intended functional shape. By housing the deflectable arms 54 together, the sheath 23 also serves to minimize vascular trauma during navigation to the target location.

[0061] The 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 the patient 28, or any other suitable skin surface.

[0062] The console 24 further comprises a magnetic sensing subsystem. The patient 28 is placed in a magnetic field generated by a pad including at least one magnetic field generator 42, which is driven by a unit 43 disposed in the console 24. The magnetic field generator 42 is configured to transmit an alternating magnetic field to a region in which a body part (e.g., the heart 26) is located. The magnetic field generated by the magnetic field generator 42 generates a directional signal in a magnetic sensor 50. The 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 the processing circuit 41.

[0063] In some 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 embodiments, processing circuitry 41 correlates position signals received from electrodes 52 and 55 with previously acquired magnetic position calibration position signals to estimate the position of catheter 40 within a heart chamber. Position coordinates of shaft electrodes 52 and 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.

[0064] Position sensing methods using current distribution measurements and / or external magnetic fields are used in various medical applications, e.g., by Biosense Webster This technique has been implemented in a Carto® system manufactured by AT&T Corporation (Irvine, Calif.) 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, International Publication No. WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1), the disclosures of which are incorporated herein by reference in their entireties.

[0065] The Carto® 3 system applies an impedance-based position tracking method of active current position (ACL). In some embodiments, the 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 the electrical impedance and a position in the magnetic coordinate frame of the field generator 42. The processing circuitry 41 estimates the positions of the shaft electrode 52 and the electrodes 55 by performing a lookup in the CPM.

[0066] The processing circuitry 41 is typically programmed with software to carry out the functions described herein. The software may be downloaded in electronic form to a computer, for example over a network, or alternatively or additionally may be provided and / or stored on a non-transitory tangible medium, such as a magnetic, optical or electronic memory.

[0067] For purposes of brevity and clarity, Figure 1 shows only those elements relevant to the disclosed technique. System 20 typically includes additional modules and elements that are not directly relevant to the disclosed technology and therefore have been intentionally omitted from Figure 1 and the corresponding description.

[0068] The catheter 40 described above includes eight deflectable arms 54 with six electrodes per arm 54. Any suitable catheter may be used in place of catheter 40, such as, for example, catheters with a different number of flexible arms and / or multiple electrodes per arm, or different probe geometries, such as, for example, balloon probes or lasso catheters.

[0069] The medical procedure system 20 may also perform ablation 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 RF power applied by one or more electrodes of a catheter connected to the console 24 and one or more body surface electrodes 49 to ablate the myocardium of the heart 26. The console 24 may include a pump (not shown) that pumps irrigation fluid into an irrigation channel to the distal end of the catheter performing the ablation. The catheter performing the ablation may further include a temperature sensor (not shown) that is used to measure the temperature of the myocardium during ablation and adjust the ablation power and / or the irrigation rate of pumping of the irrigation fluid according to the measured temperature.

[0070] Reference is now made to Figure 3, which is a flow chart 60 including exemplary steps in a method of operation of the system 20 of Figure 1. Reference is also made to Figures 1 and 2.

[0071] As previously mentioned, catheter 40 is configured to be inserted into a chamber of heart 26 of a living subject (patient 28). Catheter electrodes 55 are configured to contact tissue at respective locations within the chamber of heart 26.

[0072] The processing circuitry 41 is configured to receive (block 62) a signal from the catheter 40. The signal may be received from any of the catheter electrodes 55, shaft electrodes 52 and / or magnetic sensors 50, and in some embodiments may be received from other sensors, such as force or pressure sensors, that can provide measurements for use in assessing the quality of contact between the catheter electrodes 55 and tissue. The signal may be used to calculate the position of the catheter electrodes 55.

[0073] The processing circuitry 41 is configured to, in response to the signal, calculate (block 64) the position of the catheter electrode 55. Calculation of the position of the catheter electrode 55 may be performed based on any suitable position tracking system, for example, based on the measured impedance and / or current spread, or using the ACL method described above with reference to FIG.

[0074] The processing circuitry 41 is configured to evaluate (block 66) a respective quality of contact of each of the catheter electrodes 55 with tissue in the heart 26 in response to the signal. Any one of the catheter electrodes 55 may be in full or partial contact with tissue of the heart 26. In some cases, any one of the catheter electrodes 55 may be in contact with tissue through another liquid, such as blood of various concentrations. The quality of contact (full or partial contact, or contact through another liquid) of any one of the catheter electrodes 55 with tissue can be evaluated based on the signal provided by the catheter 40.

[0075] As mentioned above, the term "contact quality" is defined herein as a quantitative indication of the degree of electrical contact between one of the catheter electrodes 55 and tissue. As described in more detail below, "contact quality" can be expressed directly, for example, using measured electrical impedance, or indirectly, for example, using contact force, pressure, or IEGM amplitude.

[0076] As described in more detail below with reference to FIGURE 4, in some embodiments, the catheter 40 may provide a signal indicative of the impedance between the catheter electrodes 55 and the body surface electrodes 49. The impedance indication represents the quality of contact, with a higher value of impedance between one of the catheter electrodes 55 and the body surface electrodes 49 indicating a higher quality of contact between that catheter electrode 55 and the tissue. The impedance value may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes 55 and the tissue.

[0077] In some embodiments, the impedance between one of the catheter electrodes 55 on the catheter 40 and another of these catheter electrodes may be used as a measure of contact quality. As disclosed in the '529 patent mentioned in the Background section above, it is known that the impedance through blood is generally lower than the impedance through tissue. Thus, tissue contact can be assessed by comparing the impedance value of the entire set of electrodes to previously measured impedance values ​​when one electrode is known to be in good contact with tissue and when one electrode is known to be in contact only with blood.

[0078] In some embodiments, the method of U.S. Patent No. 9,168,004 to Gliner et al., incorporated herein by reference, can be used to assess contact quality. The '004 patent describes the determination of catheter electrode contact using machine learning. The '004 patent describes a cardiac catheterization method performed by storing an indication of the contact state between an electrode of the probe and the wall of the heart as in contact or not in contact, making a series of determinations of the impedance phase angle of the current flowing through this electrode and another electrode, identifying the maximum and minimum phase angles in the series of determinations, and defining a binary classifier as the midpoint between the extreme values. The test value is compared to the classifier as adjusted by a hysteresis coefficient, and if the test value is greater than or less than the adjusted classifier, a change in the constant state is reported.

[0079] In some embodiments, the catheter 40 is positioned at various positions on the deflectable arm 54 to provide signals from a force or pressure sensor (not shown) indicative of the force or pressure applied to the tissue by the catheter electrodes 55. The force or pressure indication represents a quality of contact, with higher force or pressure values ​​indicating a higher quality of contact between that catheter electrode 55 and the tissue. The force or pressure value may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes 55 and the tissue. These embodiments may use any suitable force or pressure sensor as well as any suitable method for measuring force or pressure, including those patents or patent applications mentioned in the Background section, including the method described in U.S. Patent Publication No. 2013 / 0085416 to Mest, which describes a method for in vivo recalibration of a force sensing probe such as an electrophysiology catheter that provides for the generation of an automatic zero point zone, which is incorporated herein by reference. The distal tip of the catheter or other probe is positioned within a body cavity of a patient. Verification of the absence of tissue contact is made using electrocardiogram (ECG) or impedance data, fluoroscopic imaging or other real-time imaging data, and / or an electro-anatomical mapping system. Once the absence of tissue contact is verified, the system recalibrates the signal emitted by the force sensor by setting it to correspond to a zero gram force reading, and this recalibrated baseline reading is used to generate and display a force reading based on the force sensor data.

[0080] In some embodiments, intracardiac electrogram (IEGM) traces generated by processing circuitry 41 may be used to assess the quality of contact between any one of the catheter electrodes 55 and tissue. The maximum amplitude of the IEGM trace associated with one of the catheter electrodes 55 is indicative of the quality of contact between that catheter electrode 55 and the tissue, with larger values ​​of the maximum amplitude of the IEGM trace indicating better quality of contact between that catheter electrode 55 and the tissue. The value of the amplitude of the IEGM trace may be selected to define a minimum quality of contact that is considered to represent sufficient contact between any one of the catheter electrodes 55 and the tissue.

[0081] Reference is now made to Figure 4, which is a flow chart 80 including exemplary steps in an electrical impedance-utilizing method of operation of system 20 of Figure 1. Flow chart 80 includes steps that may be performed instead of, or in addition to, the steps of blocks 64 and 66 of Figure 3. Reference is also made to Figures 1 and 2.

[0082] The processing circuitry 41 is configured to measure an indication of the electrical impedance between the body surface electrode 49 and the catheter electrode 55 (block 82). The processing circuitry 41 is configured to calculate position coordinates of the catheter electrode 55 in response to the indication of the electrical impedance (block 84). The calculation of the position coordinates may be based on any suitable position tracking method, such as the ACL method described above with reference to FIG. 1, or using a ratio of measured impedance or current distribution between the electrode 55 and the body surface electrode 49.

[0083] The processing circuitry 41 is configured to evaluate the quality of contact of each of the catheter electrodes 55 with tissue within the heart 26 in response to the indication of electrical impedance (block 86), as described in more detail with reference to FIG.

[0084] Reference is now made to Figure 5, which is a schematic illustration of a first exemplary intracardiac electrogram (IEGM) trace 88 produced by the system 20 of Figure 1. Figure 5 shows three IEGM traces 88.

[0085] Trace 88-1 represents tissue electrical activity sensed by one of the catheter electrodes 55 (FIG. 2) that was assessed as not being in sufficient contact with the cardiac tissue 26 (FIG. 1).

[0086] Trace 88-2 is highlighted using a lighter trace or a different color than that used for trace 88-1. Trace 88-2 represents tissue electrical activity sensed by one of the catheter electrodes 55 (FIG. 2) that was assessed as being in sufficient contact with the tissue.

[0087] Trace 88-3 is partially highlighted (using a lighter trace than that used for trace 88-1 or a different color than that used for trace 88-1) in region 90 corresponding to a first time when the catheter electrode 55 that sensed the electrical activity represented by trace 88-3 was assessed to be in sufficient contact with the tissue. The catheter electrode 55 was not in sufficient contact with the tissue after the first time when the contact was sufficient. A fading effect is used in region 92 of trace 88-3 corresponding to a second time after the first time. The fading effect is used to darken the brightness or color used to highlight trace 88-3 in region 90 back to the original brightness and / or color (used for the trace associated with the electrode not in sufficient contact with the tissue) after the electrode 55 associated with trace 88-3 is no longer in sufficient contact with the tissue. The fading effect may occur over any suitable time frame, such as, but not limited to, 1 to 3 seconds. The fading effect helps to smooth out changes in brightness and / or color that occur due to intermittent contact and / or changes in quality of contact.

[0088] Reference is now made to FIG. 6, which is a schematic diagram of a second exemplary intracardiac electrogram (IEGM) trace 88 produced by the system 20 of FIG. 1. FIG. 6 shows the traces 88 representing electrical activity sensed by approximately 42 catheter electrodes 55. It can be seen that identifying the catheter electrodes 55 that are in sufficient contact with tissue from the traces 88 without trace highlighting would be a very difficult, if not impossible, task for the physician 30 (FIG. 1) to perform. FIG. 6 shows that four traces 88 (labeled 88-4) are highlighted using a bright format and / or a different color compared to the other non-highlighted traces 88. These traces 88 may be displayed on the display 27 (FIG. 1) with a letter indicating which of these traces 88 correspond to which catheter electrode 55 by using any suitable identification information for each catheter electrode 55. For example, the trace 88 corresponding to the fifth catheter electrode 55 on the first one of the deflectable arms 54 may be labeled "A5," and the trace 88 corresponding to the first catheter electrode 55 on the third one of the deflectable arms 54 may be labeled "C1."

[0089] Referring again to FIG. 3, and also to FIG. 1 and FIG. 2, the processing circuitry 41 is configured to render (block 68) on the display 27 each intracardiac electrogram (IEGM) trace 88 representing electrical activity in the tissue sensed by the catheter electrodes 55 at each location in response to the signals received from the catheter 40, while modifying visual characteristics of at least some of the traces (e.g., trace 88-4 in FIG. 6) in response to a respective quality of contact of the catheter electrodes 55 with the tissue of the heart 26 at each location. In some embodiments, the processing circuitry 41 is configured to modify visual characteristics of traces (e.g., trace 88-4 in FIG. 6) representing electrical activity sensed by those of the catheter electrodes 55 that have a higher quality of contact with the tissue than a predetermined threshold quality of contact. The predetermined threshold quality of contact may be defined as described above in terms of any one or more of a predetermined impedance, a predetermined force, a predetermined pressure, and / or a predetermined IEGM amplitude, by way of example only.

[0090] In some embodiments, the processing circuitry 41 is configured to modify the visual characteristics by increasing the brightness of at least some of the traces 88 (block 70) in response to the respective quality of contact of the catheter electrodes 55 with the cardiac tissue at each location. In some embodiments, the processing circuitry is configured to increase the brightness of a trace representing electrical activity sensed by a first one of the catheter electrodes 55 having a higher quality of contact with the tissue (e.g., trace 88-4 in FIG. 6 ) relative to a trace 88 representing electrical activity sensed by a second one of the catheter electrodes 55 having a lower quality of contact with the tissue.

[0091] In some embodiments, in addition to or instead of increasing the brightness of at least some of the traces 88, the processing circuitry 41 is configured to change the color of at least some of the traces 88 in response to the respective quality of contact of the catheter electrodes 55 with the tissue of the heart 26 at each location. In some embodiments, the processing circuitry 41 is configured to change the color (and optionally increase the brightness) of a trace representing electrical activity sensed by a first one of the catheter electrodes 55 having a higher quality of contact with the tissue (e.g., trace 88-4 in FIG. 6 ) compared to a trace 88 representing electrical activity sensed by a second one of the catheter electrodes 55 having a lower quality of contact with the tissue.

[0092] As discussed above with reference to Figure 5, a fading effect can be used to indicate the time after electrode contact falls below a predetermined threshold contact quality. Processing circuitry 41 is configured to modify the visual characteristics of trace 88 (block 72) for a period of time after the contact quality falls below the predetermined threshold contact quality. The steps of block 72 are described in more detail below.

[0093] Referring again to FIG. 5, the processing circuit 41 (FIG. 1) is configured to perform a first modification (e.g., in region 90) of the visual features of one of the traces 88-3, which represents electrical activity sensed by one of the catheter electrodes 55 (FIG. 2) whose contact quality with the tissue is higher than a predetermined threshold contact quality, during a first time. The processing circuit 41 is also configured to perform a second modification (e.g., in region 92) of the visual features of the trace 88-3, which represents electrical activity sensed by one of the catheter electrodes 55 whose contact quality with the tissue is lower than a predetermined threshold contact quality, during a second time following the first time. In some embodiments, the second modification or fading effect of the visual features changes over the course of the second time. In some embodiments, the second modification or fading effect of the visual features includes darkening the visual features (and / or changing the color of the trace 88-3 back to the original color used before the first time) over the course of the second time.

[0094] Various different features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single 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.

[0095] 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 above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description.

[0096] [Embodiment] (1) A health care system, comprising: a catheter configured to be inserted into a chamber of a heart of a living subject, the catheter including catheter electrodes configured to contact tissue at locations within the chamber of the heart; A display and receiving a signal from the catheter and in response to the signal; assessing a quality of contact of each of the catheter electrodes with the tissue within the heart; rendering on the display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations, while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at each of the locations; A processing circuit configured as above; A medical system that has: (2) The system of embodiment 1, wherein the processing circuitry is configured to increase brightness of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at each of the locations. (3) The system of embodiment 2, wherein the processing circuitry is configured to increase the intensity of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a higher quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a lower quality of contact with the tissue. (4) The system of embodiment 1, wherein the processing circuitry is configured to change color of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at each of the locations. (5) The system of claim 4, wherein the processing circuitry is configured to vary the color of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a higher quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a lower quality of contact with the tissue.

[0097] (6) The system of claim 1, wherein the processing circuitry is configured to modify the visual characteristics of at least some of the traces representing the electrical activity sensed by catheter electrodes that have a contact quality with the tissue above a predetermined threshold contact quality. (7) The processing circuit, performing a first modification of the visual characteristic of one of the traces representing the electrical activity sensed by one of the catheter electrodes having a tissue contact quality greater than the predetermined threshold contact quality during a first time; performing a second modification of the visual characteristic of the one trace representing the electrical activity sensed by the one catheter electrode having a tissue contact quality below the predetermined threshold contact quality during a second time period subsequent to the first time period. The system of embodiment 6, configured as follows: (8) The system of embodiment 7, wherein the second modification of the visual characteristic changes over the second period of time. (9) The system of embodiment 8, wherein the second modification of the visual characteristic includes darkening of the visual characteristic over the second time period. (10) The system of embodiment 1, further comprising a body surface electrode configured to be affixed to a skin surface of the living subject, wherein the processing circuitry is configured to measure an indication of electrical impedance between the body surface electrode and the catheter electrode, and to calculate position coordinates of the catheter electrode in response to the indication of the electrical impedance.

[0098] (11) The system of claim 10, wherein the processing circuitry is configured to assess the respective quality of contact of each of the catheter electrodes with the tissue in the heart in response to the indication of the electrical impedance. (12) A medical method comprising: receiving a signal from a catheter configured to be inserted into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; assessing a quality of contact of each of the catheter electrodes with the tissue within the heart in response to the signals; rendering on a display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at each of the locations; A medical method comprising: 13. The method of claim 12, further comprising increasing intensity of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at the respective locations. (14) The method of embodiment 13, wherein the increasing comprises increasing the intensity of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a higher quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a lower quality of contact with the tissue. 15. The method of claim 12, further comprising changing color of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at the respective locations.

[0099] (16) The method of embodiment 15, wherein the varying comprises changing the color of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a higher quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a lower quality of contact with the tissue. (17) The method of claim 12, wherein the modifying includes modifying the visual characteristics of at least some of the traces representing the electrical activity sensed by catheter electrodes that have a contact quality with the tissue above a predetermined threshold contact quality. (18) performing a first modification of the visual characteristic of one of the traces representing the electrical activity sensed by one of the catheter electrodes having a tissue contact quality greater than the predetermined threshold contact quality during a first time; performing a second modification of the visual characteristic of the one trace representing the electrical activity sensed by the one catheter electrode having a tissue contact quality below the predetermined threshold contact quality during a second time period subsequent to the first time period; 18. The method of embodiment 17, further comprising: (19) The method of embodiment 18, wherein the second modification of the visual characteristic varies over the second time period. (20) The method of embodiment 19, wherein the second modification of the visual characteristic includes darkening of the visual characteristic over the second time period.

[0100] (21) measuring an indication of electrical impedance between a body surface electrode configured to be affixed to a skin surface of the living subject and the catheter electrode; calculating position coordinates of the catheter electrodes in response to the indication of the electrical impedance; 13. The method of embodiment 12, further comprising: (22) The method of embodiment 21, wherein the evaluating comprises evaluating the respective quality of contact of each of the catheter electrodes with the tissue in the heart in response to the indication of the electrical impedance. (23) A software product including a non-transitory computer-readable medium having program instructions stored thereon, the instructions, when read by a central processing unit (CPU), causing the CPU to: receiving signals from a catheter configured to be inserted into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; assessing a quality of contact of each of the catheter electrodes with the tissue within the heart in response to the signals; causing a display to render respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations, while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue of the heart at each of the locations. Software products.

Claims

1. 1. A health care system comprising: a catheter configured to be inserted into a chamber of a heart of a living subject, the catheter including catheter electrodes configured to contact tissue at locations within the chamber of the heart; A display and receiving a signal from the catheter and in response to the signal; assessing the quality of each of the catheter electrodes' contact with the tissue; rendering on the display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations, while modifying visual characteristics of at least some of the traces in response to the respective qualities of contact of the catheter electrodes with the tissue at each of the locations; A processing circuit configured as above; Equipped with the processing circuitry is configured to modify the visual characteristics of at least some of the traces representing the electrical activity sensed by those of the catheter electrodes that have a contact quality with the tissue above a predetermined threshold contact quality; The processing circuitry comprises: performing a first modification of the visual characteristic of one of the traces representing the electrical activity sensed by one of the catheter electrodes during a first time period during which the quality of contact with the tissue is greater than the predetermined threshold contact quality; performing a second modification of the visual features of the traces in which the first modification of the visual features was performed for a second time period if the quality of contact with the tissue falls below the predetermined threshold contact quality following the first time period; the second time comprises a preset time period. It is configured as follows: Healthcare system.

2. 2. The system of claim 1, wherein the processing circuitry is configured to increase intensity of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue at each of the locations.

3. 3. The system of claim 2, wherein the processing circuitry is configured to increase the intensity of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with the tissue.

4. 2. The system of claim 1, wherein the processing circuitry is configured to change color of at least some of the traces in response to the respective qualities of contact of the catheter electrodes with the tissue at each of the locations.

5. 5. The system of claim 4, wherein the processing circuitry is configured to vary the color of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with the tissue.

6. The system of claim 1 , wherein the second modification of the visual characteristic varies over the second time period.

7. The system of claim 6 , wherein the second modification of the visual characteristic comprises a darkening of the visual characteristic over the second time period.

8. 2. The system of claim 1, further comprising body surface electrodes configured to be affixed to a skin surface of the living subject, the processing circuitry configured to measure an indication of electrical impedance between the body surface electrodes and the catheter electrodes, and to calculate position coordinates of the catheter electrodes in response to the indication of the electrical impedance.

9. The system of claim 8 , wherein the processing circuitry is configured to assess the respective quality of contact of each of the catheter electrodes with the tissue in response to the indication of the electrical impedance.

10. 1. A method of operating a medical system comprising a catheter, a display, and a processing circuit, comprising: the processing circuit receiving signals from a catheter configured for insertion into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; the processing circuitry responding to the signals to assess a quality of contact of each of the catheter electrodes with the tissue; the processing circuitry rendering on the display respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations while modifying visual characteristics of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue at each of the locations; Including, the modifying includes the processing circuit modifying the visual characteristics of at least some of the traces representing the electrical activity sensed by those of the catheter electrodes that have a contact quality with the tissue above a predetermined threshold contact quality; the processing circuitry performing a first modification of the visual characteristics of one of the traces representing the electrical activity sensed by one of the catheter electrodes having a contact quality with the tissue greater than the predetermined threshold contact quality during a first time; the processing circuitry performing, for a second time period following the first time period, a second modification of the visual features of the traces in which the first modification of the visual features was performed if the quality of contact with the tissue falls below the predetermined threshold contact quality; the second time comprising a preset time period; and Further comprising: How the healthcare system works.

11. 11. The method of claim 10, further comprising the processing circuitry increasing a brightness of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue at each of the locations.

12. 12. The method of claim 11, wherein the increasing includes the processing circuit increasing the brightness of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with the tissue.

13. 11. The method of claim 10, further comprising the processing circuit changing a color of at least some of the traces in response to the respective quality of contact of the catheter electrodes with the tissue at each of the locations.

14. 14. The method of claim 13, wherein the varying includes the processing circuit changing the color of the trace representing the electrical activity sensed by a first one of the catheter electrodes having a better quality of contact with the tissue compared to the trace representing the electrical activity sensed by a second one of the catheter electrodes having a worse quality of contact with the tissue.

15. The method of claim 10 , wherein the second modification of the visual characteristic varies over the second time period.

16. The method of claim 15 , wherein the second modification of the visual characteristic comprises a darkening of the visual characteristic over the second time period.

17. the processing circuitry measuring an indication of electrical impedance between a body surface electrode configured to be affixed to a skin surface of the living subject and the catheter electrode; the processing circuitry calculating position coordinates of the catheter electrodes in response to the indication of the electrical impedance; The method of claim 10 further comprising:

18. 18. The method of claim 17, wherein the evaluating includes the processing circuitry evaluating the respective quality of contact of each of the catheter electrodes with the tissue in response to the indication of the electrical impedance.

19. 1. A software product including a non-transitory computer readable medium having program instructions stored thereon, the program instructions, when read by a central processing unit (CPU), causing the CPU to: receiving signals from a catheter configured to be inserted into a chamber of a heart of a living subject and including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart; assessing a quality of contact of each of the catheter electrodes with the tissue in response to the signals; causing a display to render respective intracardiac electrogram (IEGM) traces representative of electrical activity in the tissue sensed by the catheter electrodes at each of the locations, while modifying visual characteristics of at least some of the traces in response to the respective qualities of contact of the catheter electrodes with the tissue at each of the locations; the modifying comprises modifying the visual characteristics of at least some of the traces representing the electrical activity sensed by catheter electrodes that have a contact quality with the tissue above a predetermined threshold contact quality; performing a first modification of the visual characteristic of one of the traces representing the electrical activity sensed by one of the catheter electrodes having a contact quality with the tissue above the predetermined threshold contact quality during a first time; performing a second modification of the visual features of the traces in which the first modification of the visual features was performed for a second time period if the quality of contact with the tissue falls below the predetermined threshold contact quality following the first time period; the second time comprises a preset time period. Software products.

Images