WO2008157399A1 - Système et procédé de détermination de contact électrode-tissu - Google Patents

Système et procédé de détermination de contact électrode-tissu Download PDF

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Publication number
WO2008157399A1
WO2008157399A1 PCT/US2008/066979 US2008066979W WO2008157399A1 WO 2008157399 A1 WO2008157399 A1 WO 2008157399A1 US 2008066979 W US2008066979 W US 2008066979W WO 2008157399 A1 WO2008157399 A1 WO 2008157399A1
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WIPO (PCT)
Prior art keywords
electrode
contact
tissue
phase difference
medical probe
Prior art date
Application number
PCT/US2008/066979
Other languages
English (en)
Inventor
Brian P. Wilfley
Joseph A. Heanue
Stuart L. Friedman
Edward G. Solomon
Original Assignee
Hansen Medical, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/762,779 external-priority patent/US20080312521A1/en
Priority claimed from US11/762,778 external-priority patent/US8160690B2/en
Application filed by Hansen Medical, Inc. filed Critical Hansen Medical, Inc.
Publication of WO2008157399A1 publication Critical patent/WO2008157399A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1492—Probes or electrodes therefor having a flexible, catheter-like structure, e.g. for heart ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/279—Bioelectric electrodes therefor specially adapted for particular uses
    • A61B5/28—Bioelectric electrodes therefor specially adapted for particular uses for electrocardiography [ECG]
    • A61B5/283—Invasive

Definitions

  • the invention generally relate to medical probes or instruments, and more particularly to systems and methods for determining contact between a medical probe or instrument and tissue.
  • a physician may steer an electrophysiology mapping catheter, typically under fluoroscopy, through a main vein or artery into the interior region of the heart that is to be treated.
  • the physician then may determine the source of the cardiac rhythm disturbance (i.e., the targeted heart tissue) either strictly by anatomical considerations or by placing mapping elements carried by the catheter into contact with the heart tissue, and operating the mapping catheter to generate an electrophysiology map of the interior region of the heart.
  • a radio frequency (RF) ablation catheter (which may or may not be the same catheter as the mapping catheter above) into the heart and places an ablation electrode in the blood stream against the targeted heart tissue carried by the catheter tip near the targeted heart tissue, and directs RF energy from the ablating element to ablate the tissue and form a lesion, thereby treating the cardiac disturbance. It is important that the contact between the electrode and the tissue be maximized to direct the RF energy toward the targeted heart tissue rather than through the blood stream.
  • RF radio frequency
  • Robotic systems that automatically manipulate catheters in response to movements of a control device at a remote user interface have recently been developed. Such systems are operated without direct manual manipulation of the instruments, and thus a physician cannot rely on directly-transmitted tactile feedback, but instead, may rely upon feedback provided by the robotic system, such as visual, audible, and/or tactile feedback, to maintain precision control over the subject instrument or instruments. It is preferred that such robotic systems be enabled with multiple means for determining the extent of contact or force between instrument electrodes and tissue.
  • a method of monitoring contact between a medical probe e.g., an intravascular catheter
  • tissue e.g., heart tissue
  • the method comprises introducing the medical probe into a patient (e.g., within a heart chamber) adjacent the tissue, and measuring an electrical parameter (e.g., an electrical admittance) between a first electrode of the medical probe and a second electrode remote from the first electrode, wherein the electrical parameter is amplitude modulated by a physiological cycle of the patient (e.g., a respiratory cycle or heart cycle).
  • an electrical parameter e.g., an electrical admittance
  • the first electrode may be a tip electrode
  • the second electrode may be a ground patch electrode attached to the skin of the patient or another electrode of the medical probe.
  • One method comprises transmitting a time varying signal between the first electrode and the second electrode, and detecting the time varying signal, wherein the electrical parameter measurement is based on the detection of the time varying signal.
  • the method further comprises detecting contact between the medical probe (e.g., the first electrode) and the tissue based on the amplitude modulation of the measured electrical parameter.
  • the contact detection may comprise comparing a magnitude of the amplitude modulation to a threshold, and determining that the medical probe is in contact with the tissue if the magnitude of the amplitude modulation exceeds the threshold.
  • the contact detection comprises determining an extent of the contact based on a magnitude of the amplitude modulation.
  • Another optional method comprises performing a medical procedure on the tissue when the contact between the medical probe and the tissue has been detected.
  • a medical system comprises a medical probe (e.g., an intravascular catheter) having a probe shaft and a first electrode (e.g., a tip electrode) carried by the probe shaft.
  • the medical system further comprises a second electrode; for example, a ground patch electrode configured for being attached to the skin of the patient or another electrode carried by the probe shaft.
  • the system further comprises a monitoring device configured for measuring an electrical parameter (e.g., an electrical admittance) between the first electrode and the second electrode, wherein the electrical parameter is amplitude modulated by a physiological cycle of the patient (e.g., a respiratory cycle or heart cycle).
  • the monitoring device may be configured for transmitting a time varying signal between the first electrode and the second electrode, and detecting the time varying signal, wherein the electrical parameter measurement is based on the detection of the time varying signal.
  • the monitoring device is configured for conveying an output to a user indicative of contact between the medical probe (e.g., the first electrode) and the tissue, the output being based on the amplitude modulation of the measured electrical parameter.
  • the monitoring device may be configured for comparing a magnitude of the amplitude modulation to a threshold, and determining that the medical probe is in contact with the tissue if the magnitude of the amplitude modulation exceeds the threshold.
  • the output is a visual display of the amplitude modulation of the measured electrical parameter.
  • the monitoring device is configured for determining an extent of the contact based on a magnitude of the amplitude modulation.
  • the system may comprise a radio frequency (RF) generator configured for delivering ablation energy to the first electrode.
  • RF radio frequency
  • a tissue contact monitoring device comprising an electrical terminal configured for coupling to a medical probe having a first electrode, and a processor configured for measuring an electrical parameter (e.g., an electrical admittance) between the first electrode and a second electrode, wherein the electrical parameter is amplitude modulated by a physiological cycle of the patient (e.g., a respiratory cycle or heart cycle).
  • the monitoring device may comprise a signal generator configured for transmitting a time varying signal between the first electrode and the second electrode, and a signal detector configured for detecting the time varying signal, wherein the processor is configured for measuring the electrical parameter based on the detected time varying signal.
  • the monitor further comprises a user interface configured for conveying an output indicative of contact between the medical probe and the tissue, the output being based on the amplitude modulation of the measured electrical parameter.
  • the processor may be configured for comparing a magnitude of the amplitude modulation to a threshold, and determining that the medical probe is in contact with the tissue if the magnitude of the amplitude modulation exceeds the threshold.
  • the user interface comprises a video monitor and the output is a visual display of the amplitude modulation of the measured electrical parameter.
  • the monitoring device is configured for determining an extent of the contact based on a magnitude of the amplitude modulation.
  • a medical probe e.g., an intravascular catheter
  • tissue e.g., heart tissue
  • the medical probe has a first tip electrode and a second electrode (e.g., a ring electrode) proximal to the first tip electrode.
  • the method comprises introducing the medical probe into a patient (e.g., within a heart chamber) adjacent the tissue.
  • the method further comprises transmitting a time varying signal to or from the second electrode, and sensing the time varying signal at the first tip electrode.
  • the method further comprises determining a phase difference between the transmitted signal and the sensed signal at the first tip electrode, and detecting contact between the first tip electrode and the tissue based on the determined phase difference.
  • the contact detection comprises comparing the phase difference to a threshold, and determining that the medical probe is in contact with the tissue if the phase difference exceeds the threshold. In another method, the contact detection comprises determining an extent of the contact based on the phase difference. If the medical probe has a third electrode proximal to the first tip electrode, the method may further comprise sensing the time varying signal at the third electrode and determining another phase difference between the transmitted signal and the sensed signal at the third electrode, wherein the contact detection is further based on the other determined phase difference. Another optional method comprises performing a medical procedure on the tissue when the contact between the medical probe and the tissue has been detected.
  • the medical system comprises a medical probe (e.g., an intravascular catheter) having a first tip electrode and a second electrode (e.g., a ring electrode) proximal to the first tip electrode.
  • the system further comprises a tissue contact monitoring device configured for transmitting a time varying signal to or from the second electrode, sensing the time varying signal at the first tip electrode, determining a phase difference between the transmitted signal and the sensed signal at the first tip electrode, and conveying an output to a user indicative of contact between the first tip electrode and the tissue, the output being based on the determined phase difference.
  • monitoring device is configured for comparing the phase difference to a threshold, and determining that the medical probe is in contact with the tissue if the phase difference exceeds the threshold. In another embodiment, the monitoring device is configured for determining an extent of the contact based on the phase difference. In still another embodiment, the output is a visual display of the phase difference.
  • the medical probe has a third electrode proximal to the first tip electrode, in which case, the monitoring device may further be configured for sensing the time varying signal at the third electrode, and determining another phase difference between the transmitted signal and the sensed signal at the third electrode, wherein the contact detection is further based on the other determined phase difference.
  • the system optionally comprises a radio frequency (RF) generator configured for delivering ablation energy to the first tip electrode.
  • RF radio frequency
  • the monitoring device comprises an electrical terminal configured for coupling to a medical probe having a first tip electrode and a second electrode proximal to the first tip electrode.
  • the monitoring device further comprises a processor configured for transmitting a time varying signal to or from the second electrode, sensing the time varying signal at the first tip electrode, and determining a phase difference between the transmitted signal and the sensed signal at the first tip electrode.
  • the monitoring device further comprises a user interface configured for conveying an output indicative of contact between the first tip electrode and the tissue, the output being based on the determined phase difference.
  • the processor is configured for comparing the phase difference to a threshold, and determining that the medical probe is in contact with the tissue if the phase difference exceeds the threshold. In another embodiment, the processor is configured for determining an extent of the contact based on the phase difference. In still another embodiment, the user interface comprises a video monitor, and the output is a visual display of the phase difference. In an optional embodiment, the monitoring device is further configured for sensing the time varying signal at the third electrode, and determining another phase difference between the transmitted signal and the sensed signal at the third electrode, wherein the contact detection is further based on the other determined phase difference.
  • Fig. 1 is a functional block diagram of one embodiment of an electrophysiology (EP) system constructed in accordance with the invention
  • Fig. 2 is a plot illustrating a measured electrical admittance of tissue, as amplitude modulated over time by a cardiac and respiratory cycle
  • Figs. 3A-3D are plots illustrating the amplitude modulation of a measured electrical admittance over a single heart beat at various frequencies
  • Fig. 4 is a block diagram of one embodiment of an electrode-tissue contact monitor used in the EP system of Fig. 1 ;
  • Fig. 5 is a side view of the distal end of the catheter used in the EP system of
  • Fig. 1 particularly showing a circuit representation of the tissue/blood surrounding the catheter
  • Fig. 6 is a block diagram of another embodiment of an electrode-tissue contact monitor used in the EP system of Fig. 1 ; and Figs. Ik-IC are side views illustrating a method of using the EP system of Fig. 1 to map and ablate aberrant regions in a heart.
  • FIG. 1 an exemplary electrophysiology (EP) system 10 constructed in accordance with the invention is shown.
  • the EP system 10 is particularly suited for mapping a heart by identifying a target tissue site or sites, e.g., aberrant conductive pathways, and for treating the heart by ablating the target tissue site(s).
  • a target tissue site or sites e.g., aberrant conductive pathways
  • the concepts disclosed herein may be applied to any process requiring the introduction of a medical probe within a patient's body to diagnose or treat other internal anatomical structures, e.g., the prostrate, brain, gall bladder, uterus, esophagus and other regions in the body.
  • the EP system 10 generally comprises a mapping/ablation catheter 12, and a mapping processor 14, a radio frequency (RF) generator 16, and an electrode-tissue contact monitor 18 functionally coupled to the mapping/ablation catheter 12 via a cable assembly 20.
  • the mapping/ablation catheter 12 may optionally be mechanically manipulated by a robotic system (not shown). Exemplary robotic systems that can be used to mechanically manipulate the catheter 12 are described in U.S. Patent No. 7,090,683 and U.S. Patent Publication No. 2006/0084945. It should be noted that the mapping processor 14, RF generator 16, and electrode- tissue contact monitor 18 are functional in nature, and thus, their illustration in Fig. 1 is not meant to limit the structure that performs these functions in any manner.
  • mapping processor 14, RF generator 16, and electrode-tissue contact monitor 18 may be embodied in a single device, or each of the mapping processor 14, RF generator 16, or electrode-tissue contact monitor 18 may be embodied in several devices. Also, the functions of these elements can be performed in hardware, software, firmware, or any combination thereof.
  • the mapping/ablation catheter 12 comprises an elongate catheter member 22, a plurality of electrodes 24, 26, 28 (in this case, three) carried at the distal end of the catheter member 22, and a handle 30 carried at the proximal end of the catheter member 22. All three electrodes 24, 26, 28 on the catheter member 22 are configured to detect electrical signals in the myocardial tissue for subsequent identification of target sites.
  • the distal-most electrode 24 takes the form of a cap electrode disposed at the distal tip 28 of the catheter member 22, and is configured to be used as an ablation electrode to provide ablation energy to the targeted sites when placed adjacent thereto and operated.
  • the electrodes 24, 26 proximal to the electrode 24 take the form of ring electrodes disposed about the catheter member 22 in a suitable manner.
  • the handle 30 includes an electrical connector 32 for electrical coupling to the mapping processor 14, RF generator 16, and electrode-tissue contact processor 18 via the cable assembly 20.
  • the mapping processor 14 is configured to derive activation times and voltage distribution from the electrical signals obtained from the electrodes (both the tip electrode 24 and the more proximally located ring electrodes 26, 28) to determine irregular electrical signals within the heart, which can then be graphically displayed as a map. Mapping of tissue within the heart is well known in the art, and thus for purposes of brevity, the mapping processor 14 will not be described in further detail. Further details regarding electrophysiology mapping are provided in U.S. Patent Nos. 5,485,849, 5,494,042, 5,833,621 , and 6,101 ,409.
  • the RF generator 16 is configured to deliver ablation energy to the ablation electrode (i.e., the tip electrode 24) in a controlled manner in order to ablate sites identified by the mapping processor 14.
  • ablation energy i.e., the tip electrode 24
  • other types of ablative sources besides the RF generator 16 can be used, e.g., a microwave generator, an acoustic generator, a cryoablation generator, and a laser or other optical generator.
  • Ablation of tissue within the heart is well known in the art, and thus for purposes of brevity, the RF generator 16 will not be described in further detail. Further details regarding RF generators are provided in U.S. Patent No. 5,383,874.
  • the RF current is delivered to the tip electrode 24 in a monopolar fashion, which means that current will pass from the tip electrode 24, which is configured to concentrate the energy flux in order to have an injurious effect on the surrounding tissue, and a dispersive ground patch electrode (not shown), which is located remotely from the tip electrode 24 and has a sufficiently large area (typically 130 cm 2 for an adult), so that the current density is low and non- injurious to surrounding tissue.
  • the dispersive electrode may be attached externally to the patient, e.g., using a contact pad placed on the patient's flank.
  • the RF current is delivered to the tip electrode 24 in a multipolar (e.g., bipolar) fashion, which means that current will pass between the tip electrode 24 and one or both of the ring electrodes 26, thereby concentrating the energy flux in order to have an injurious effect on the tissue between the tip electrode 24 and ring electrodes 26, 28.
  • a catheter having a basket structure of resilient splines, each of which carries a plurality of dedicated mapping electrodes can be used.
  • This catheter may be placed in a heart chamber, so that the resilient splines conform to the endocardial surface of the heart, thereby placing and distributing the mapping electrodes along the entire endocardial surface of the cavity for efficient mapping.
  • the catheter may also have a roving ablation electrode that can be steered in contact with the ablation sites identified by the mapping electrodes. Or a separate ablation catheter with a dedicated ablation electrode or electrodes can be used.
  • the electrode-tissue contact monitor 18 measures an electrical parameter, and in particular electrical admittance, between the tip electrode 24 and the ground patch electrode (not shown) to detect both the occurrence and extent of catheter contact with heart tissue. Alternatively, the monitor 18 may measure the electrical admittance between the tip electrode 24 and one or both of the ring electrodes 26, 28.
  • the electrical admittance measured by the monitor 18 is amplitude modulated by a physiological cycle of the patient in which the mapping/ablation catheter 12 is introduced.
  • the monitor 18 can detect both the occurrence and extent to which the tip electrode 24 contacts heart tissue based on this amplitude modulation.
  • a physiological cycle e.g., a heart cycle or a respiratory cycle.
  • an electrical admittance measured within the heart of a pig is shown amplitude modulated (shown by the curves in upper graph) by both the heart cycle and the respiratory cycle (shown by the electrocardiogram (EKG) of lower graph).
  • EKG electrocardiogram
  • a tissue ablation electrode was placed within the atrium of a live pig and a ground patch electrode was placed on the skin of the pig. The admittance between the electrodes were then measured, while the ablation electrode was not placed in contact with the heart tissue (i.e., fully immersed in the blood pool) placed in contact with the blood pool, and while the ablation electrode was placed in contact with the heart tissue, as confirmed via fluoroscopy.
  • the measured electrical admittance when the ablation electrode is not in contact with the heart tissue has a baseline level (approximately, 11.5 mS) that is higher than the baseline level (approximately, 8 mS) of the measured admittance when the ablation electrode is in contact with the heart tissue (bottom curve in upper graph).
  • the magnitude that the measured admittance is amplitude modulated by the heart and respiratory cycles relative to the baseline is relatively small (approximately .1 mS).
  • the magnitude that the measured admittance is amplitude modulated by the heart and respiratory cycles relative to the baseline is relatively large (approximately 2.5 mS).
  • the magnitude of the amplitude modulation increases with an increase in contact between the ablation electrode and heart tissue.
  • the presence of amplitude modulation of the admittance measurement is a reliable indicator of whether an electrode is in or is not in contact with heart tissue, and the magnitude of the amplitude modulation of the admittance measurement is a reliable indicator of the quality of contact between the electrode and heart tissue.
  • the measured admittance has both a slow modulation (envelope of waveform) that tracks the respiratory cycle of the pig, and a fast modulation that tracks the heart cycle of the pig.
  • the occurrence and extent of contact between an electrode and heart tissue may be determined based on the amplitude modulation caused by either or both of the respiratory cycle and cardiac cycle.
  • the impedance and thus the baseline levels of the measured admittance, will vary among patients. If only the baseline level of the admittance is measured, variations in the conductance of patient's heart tissue or blood would need to be calibrated out. Significantly, however, the magnitude of the amplitude modulation of a measured admittance, does not vary among patients. Thus, if the amplitude of the amplitude modulation is measured, variations in the conductance of patient's heart tissue or blood would not need to be calibrated out using a separate technique.
  • Figs. 3A-3D the magnitude of the admittance is shown for a single heartbeat over four difference frequencies.
  • the magnitude of the measured admittance when the ablation electrode is not in contact with the heart tissue is less than the magnitude of the measured admittance when the ablation electrode is in contact with the heart tissue (dotted curve).
  • the measured non-contact admittance remains relatively uniform in response to the single heart beat (solid EKG curve), whereas the measured contact admittance markedly increases in response to the single heart beat. For example, at a frequency of 1 KHz (Fig.
  • the measured non-contact admittance remains at approximately 5.8 mS, whereas the measured contact admittance increases from approximately 4.5 mS to approximately 5 mS.
  • the measured non-contact admittance remains at approximately 10 mS, whereas the measured contact admittance increases from approximately 7.5 mS to approximately 8.2 mS.
  • the measured non-contact admittance remains at approximately 11 mS, whereas the measured contact admittance increases from approximately 8.2 mS to approximately 9.0 mS.
  • a frequency of 100 KHz Fig.
  • Figs. 3A-3D illustrate the modulation of the measured contact admittance as occurring prior to the EKG reading, reflecting the fact that the admittance measurement is being performed in the atrium, while the EKG is measured within the ventricle. In fact, the modulation of the measured contact admittance will be temporally coincident with the depolarization of the atrial heart tissue. It is apparent from Figs.
  • the noise is very low, and thus, the signal-to-noise ratio is very high, thereby providing admittance measurements that very accurately represent true electrode-tissue contact and are very sensitive to electrode-tissue contact changes.
  • the frequency range that produces clear admittance measurements is within the safe frequency range during normal operation of approximately 50-100 KHz.
  • the electrode-tissue contact monitor 18 utilizes the amplitude modulation concept illustrated in Figs. 2 and 3A-3D to detect the occurrence and extent of contact between the tip electrode 24 of the mapping/ablation catheter 12 and heart tissue.
  • the monitor 18 comprises an electrical terminal 34 to which the cable assembly 20 is mated, thereby coupling the catheter 12 (in particular, the electrodes 24, 26, 28) and ground patch electrode (not shown) to the monitor 18.
  • the monitor 18 further comprises a signal generator 36 configured for transmitting a time varying signal (e.g., a sinusoidal wave having a frequency between 1 KHz to 100KHz) between the tip electrode 24 and ground patch electrode (alternatively, the ring electrodes 26), and a signal detector 38 configured for sensing the magnitude of the voltage (if the signal generator 36 has a constant current source) or current (if the signal generator 36 has a constant voltage source) of the time varying signal.
  • a time varying signal e.g., a sinusoidal wave having a frequency between 1 KHz to 100KHz
  • a signal detector 38 configured for sensing the magnitude of the voltage (if the signal generator 36 has a constant current source) or current (if the signal generator 36 has a constant voltage source) of the time varying signal.
  • the electrical admittance between the tip electrode 24 and ground electrode, and thus, the voltage or current sensed by the signal detector 38 will be amplitude modulated by either the heart cycle or the respiratory cycle.
  • the monitor 18 comprises a processor 40 configured for detecting contact between the tip electrode 24 and tissue based on the amplitude modulation of sensed by the signal detector 38.
  • the processor 40 compares the sensed magnitude of the amplitude modulation (i.e., the difference between the peak amplitude to the baseline amplitude) to a threshold level, and determines that the tip electrode 24 is in contact with the heart tissue if the magnitude of the amplitude modulation exceeds the threshold level, and determines that the tip electrode 24 is not in contact with the heart tissue otherwise. If it is determined that the tip electrode 24 is in contact with the heart tissue, the processor 40 is configured for determining an extent of the electrode-tissue contact based on a magnitude of the sensed amplitude modulation.
  • a look-up table containing amplitude modulation values and corresponding values indicative of the extent of contact.
  • corresponding values can be, e.g., a position of the electrode relative to the undeflected surface of the heart tissue or a percentage of the area of the electrode covered by the heart tissue.
  • the look-up table can, e.g., be generated based on empirical or modeled data.
  • the extent of contact can be determined based on one or more closed-form equations, in which the magnitude of the amplitude modulation is input and out which the contact values are output.
  • the processor 40 may generate a warning signal indicating that contact between the tip electrode 24 and the heart tissue is dangerously close to the puncturing or otherwise inadvertently damaging the heart tissue. If a robotic system is used, the processor 40 may transmit a signal to the robotic system preventing further advancement of the catheter 12.
  • the monitor 18 further comprises a user interface 42 configured for conveying an output indicative of contact between the tip electrode 24 and the heart tissue.
  • the user interface 42 includes a video monitor (not shown) configured to display the contact values determined by the processor 40.
  • the user interface 42 may include a speaker (not shown) configured to audibly output the contact values. If the processor 40 generates a warning signal, the user interface 42 may also output the warning signal in the form of, e.g., a flashing icon on the video monitor or an audible sound from the speaker.
  • the user interface 42 simply outputs the amplitude modulation of the electrical admittance; that is, the measured electrical admittance over time. In this case, the processor 40 merely processes the magnitude of the voltage or current detected by the signal detector 38 for output as an electrical admittance to the user interface 42.
  • the occurrence and extent to which an electrode contacts heart tissue can also be determined based on a phase difference between the electrode and another electrode known to be not in contact with the heart tissue.
  • a time- varying signal can be transmitted between the ring electrode 26 and ground, and then measured at the tip electrode 24 to form the circuit illustrated in Fig. 5.
  • the circuit comprises a sinusoidal voltage source having a value V1 equal to the voltage of the time-varying signal supplied to the ring electrode 26, and a voltage V2 equal to the voltage of the time-varying signal measured by the tip electrode 24.
  • Resistance R1 and capacitance C1 represent the impedance between the ring electrode 26 and the tip electrode 24, and resistance R2 and capacitance C2 represent the impedance between the tip electrode 24 and ground.
  • phase difference between voltages V1 and V2 i.e., the voltage generated at the ring electrode 26 and the voltage measured at the tip electrode 24
  • the phase difference between voltages V1 and V2 will increase as the contact between the tip electrode 24 and the tissue increases (i.e., as the area of the tip electrode 24 covered by the tissue increases).
  • the time-varying voltage can also be measured at the ring electrode 26, as well as the tip electrode 24, to provide additional information.
  • the phase of the voltage measured at the ring electrode 28 can be compared to the phase of the voltage generated at the ring electrode 26 to confirm that the tip electrode 24 is, indeed, not in contact with the tissue; that is, no phase difference will confirm non- contact between the tip electrode 24 and tissue.
  • the phase of the voltage measured at the electrode 28 can be compared to the phase of the voltage generated at the ring electrode 26 to confirm that the tip electrode 24 is, indeed, in contact with the tissue; that is, a phase difference will confirm contact between the tip electrode 24 and tissue.
  • an electrode-tissue contact monitor 118 utilizes the voltage phase difference concept illustrated in Fig. 5, as alternative to or in addition to the amplitude modulation concept, to detect the occurrence and extent of contact between the tip electrode 24 of the ablation/mapping catheter 12 and the heart tissue.
  • the monitor 118 comprises an electrical terminal 134 to which the cable assembly 20 is mated, thereby coupling the catheter 12 (in particular, the electrodes 24, 26, 28) and ground patch electrode (not shown) to the monitor 118.
  • the monitor 118 further comprises a signal generator 136 configured for transmitting a time varying signal (e.g., a sinusoidal wave having a frequency between 1KHz to 100KHz) between the ring electrode 26 (alternatively, the ring electrode 28) and the ground patch electrode, a first signal detector 138(1) configured for sensing the phase of the voltage of the time varying signal, and a second signal detector 138(2) configured for sensing the phase of the voltage of the time varying signal measured between the tip electrode 24 and the ground patch electrode.
  • the monitor 118 may comprise a third signal detector 138(3) configured for sensing the phase of the voltage of the time varying signal measured between the ring electrode 28 not supplied with the time varying signal and the ground patch electrode.
  • the monitor 18 comprises a processor 140 configured for detecting contact between the tip electrode 24 and tissue based on the voltage phases sensed by the first and second signal detectors 138(1) and 138(2).
  • the processor 140 subtracts the voltage phase detected by the first signal detector 138(1) from the voltage phase sensed by the second signal detector 138(2) (or vice versa), and determines that the tip electrode 24 is in contact with the heart tissue if the magnitude of the phase difference exceeds a threshold level, and determines that the tip electrode 24 is not in contact with the heart tissue otherwise.
  • the processor 140 may subtract the voltage phase sensed by the first signal detector 138(1) from the voltage phase sensed by the third signal detector 138(3)(or vice versa), and if the tip electrode 24 is determined to be contact with the tissue in the first instance, confirms this if the magnitude of the phase difference sensed by the first and third signal detectors 138(1), 138(3) exceeds a threshold level, and if the tip electrode 24 is determined to not be contact with the tissue in the first instance, confirms this if the magnitude of the phase difference sensed by the first and third signal detectors 138(1), 138(3) does not exceed the threshold level.
  • the processor 140 is configured for determining an extent of the electrode-tissue contact based on a magnitude of the phase difference. This can be accomplished, e.g., by accessing a look-up table containing voltage phase difference values and corresponding values indicative of the extent of contact. Such corresponding values can be, e.g., a position of the electrode relative to the undeflected surface of the tissue or a percentage of the area of the electrode covered by the tissue.
  • the lookup table can, e.g., be generated based on empirical or modeled data.
  • the extent of contact can be determined based on one or more closed-form equations, in which the magnitude of the phase difference is input and out which the contact values are output.
  • the processor 140 may generate a warning signal indicating that contact between the tip electrode 24 and the tissue is dangerously close to the puncturing or otherwise inadvertently damaging the tissue.
  • the monitor 118 further comprises a user interface 142 configured for conveying an output indicative of contact between the tip electrode 24 and the tissue.
  • the user interface 42 includes a video monitor (not shown) configured to display the contact values determined by the processor 40.
  • the user interface 142 may include a speaker (not shown) configured to audibly output the contact values.
  • the user interface 42 may also output the warning signal in the form of, e.g., an flashing icon on the monitor 118 or an audible sound from the speaker.
  • the user interface 142 simply outputs the phase difference.
  • the processor 140 merely processes the phase difference for output to the user interface 142. If a robotic system is used, the processor 140 may transmit a signal to the robotic system preventing further advancement of the catheter 12.
  • the extent to which the heart tissue wraps around the electrode can be determined, which may actually be more useful than determining force, since the heart walls of different patients will puncture at different applied forces. For example, given the same applied force, a thin heart wall, which may typically be found in older patients, will puncture before a thicker heart wall.
  • the thinner heart wall will wrap around an electrode more than a thicker heart wall given the same applied force, the measured contact admittance will be greater with respect to the thinner heart wall than the thicker heart wall, thereby providing a more reliable means for preventing puncture, as well as a more reliable means for indicating the occurrence of tissue tenting when desired.
  • depth of electrode insertion into heart tissue is a better indication of electrode-tissue contact sufficient for ablation than is applied force.
  • the mapping/ablation catheter 12 is intravenously introduced into the appropriate chamber of the heart H, into the appropriate chamber of the heart H (Fig. 7A). For example, if the disease to be treated is ventricular tachycardia, the catheter 12 will be introduced into the left ventricle. If the disease to be treated is atrial fibrillation, the catheter 12 will be introduced into the left atrium.
  • the electrode-tissue contact monitor 18 may be operated to determine the extent of contact between the tip electrode 24 and the heart tissue. This may especially be useful if the catheter 12 is being manipulated by a robotic system.
  • the catheter 12 is then moved around within the selected chamber of the heart H as the mapping processor 14 is operated to record electrical activity within the heart 10 and derive mapping data therefrom. If an aberrant region AR identified, the tip electrode 24 of the mapping/ablation catheter 12 is placed into contact with the aberrant region AR (Fig. 7B).
  • the electrode-tissue contact monitor 18 (or alternatively, monitor 118) may again be operated to determine the occurrence and extent of contact between the tip electrode 24 and the heart tissue.
  • the RF generator 36 is then operated to therapeutically create a lesion L at the aberrant region AR (Fig. 7C).
  • the electrode-tissue contact monitor 18 (or alternatively, the monitor 118) may be operated to ensure that proper and firm contact between the tip electrode 24 and the heart tissue is maintained.
  • the mapping processor 14 can again be operated to ensure that the heart disease has been successfully treated. If additional aberrant conductive pathways have been found, the ablation step can be repeated. If no aberrant conductive pathways have been found, the catheter 12 can then be removed from the patient.

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Abstract

La présente invention concerne des procédés et des systèmes permettant de surveiller le contact entre une sonde médicale et un tissu. Une sonde médicale est introduite dans un patient en position adjacente au tissu. Dans une technique, un paramètre électrique, par exemple l'admittance, est mesuré entre une première électrode située sur la sonde médicale et une seconde électrode éloignée de la première électrode. Le paramètre électrique est modulé en amplitude en réponse à un cycle physiologique du patient. Le contact entre la sonde médicale et le tissu est détecté sur la base de la modulation d'amplitude du paramètre électrique mesuré. Dans une autre technique, un signal variant dans le temps est transmis à la seconde électrode ou depuis celle-ci, le signal variant dans le temps est capté au niveau de l'extrémité de la première électrode, une différence de phase entre le signal transmis et le signal capté est déterminée, et un contact entre l'extrémité de la première électrode et le tissu est détecté sur la base de la différence de base déterminée.
PCT/US2008/066979 2007-06-14 2008-06-13 Système et procédé de détermination de contact électrode-tissu WO2008157399A1 (fr)

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US11/762,779 US20080312521A1 (en) 2007-06-14 2007-06-14 System and method for determining electrode-tissue contact using phase difference
US11/762,778 US8160690B2 (en) 2007-06-14 2007-06-14 System and method for determining electrode-tissue contact based on amplitude modulation of sensed signal
US11/762,779 2007-06-14
US11/762,778 2007-06-14

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Cited By (16)

* Cited by examiner, † Cited by third party
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WO2010082145A2 (fr) 2009-01-15 2010-07-22 Koninklijke Philips Electronics N.V. Sonde d'électrophysiologie
US8160690B2 (en) 2007-06-14 2012-04-17 Hansen Medical, Inc. System and method for determining electrode-tissue contact based on amplitude modulation of sensed signal
CN105078569A (zh) * 2014-05-22 2015-11-25 南京医科大学第一附属医院 交感神经标测消融装置及系统
WO2017070559A1 (fr) * 2015-10-21 2017-04-27 St. Jude, Cardiology Division, Inc. Cathéter de cartographie à électrodes de haute densité
US10362954B2 (en) 2015-10-21 2019-07-30 St. Jude Medical, Cardiology Division, Inc. High density electrode mapping catheter
US10555672B2 (en) 2012-11-19 2020-02-11 Biosense Webster (Israel) Ltd. Using location and force measurements to estimate tissue thickness
JP2020108775A (ja) * 2018-12-28 2020-07-16 バイオセンス・ウエブスター・（イスラエル）・リミテッドＢｉｏｓｅｎｓｅ Ｗｅｂｓｔｅｒ （Ｉｓｒａｅｌ）， Ｌｔｄ． 接触を検出するための多相アブレーション発生器の位相の調整
US11382650B2 (en) 2015-10-30 2022-07-12 Auris Health, Inc. Object capture with a basket
US11433220B2 (en) 2017-07-07 2022-09-06 St. Jude Medical, Cardiology Division, Inc. Layered high density electrode mapping catheter
US11439419B2 (en) 2019-12-31 2022-09-13 Auris Health, Inc. Advanced basket drive mode
US11534249B2 (en) 2015-10-30 2022-12-27 Auris Health, Inc. Process for percutaneous operations
US11540876B2 (en) 2016-05-03 2023-01-03 St. Jude Medical Cardiology Division, Inc. Irrigated high density electrode catheter
US11571229B2 (en) 2015-10-30 2023-02-07 Auris Health, Inc. Basket apparatus
US11642063B2 (en) 2018-08-23 2023-05-09 St. Jude Medical, Cardiology Division, Inc. Curved high density electrode mapping catheter
US11826172B2 (en) 2014-05-06 2023-11-28 St. Jude Medical, Cardiology Division, Inc. Electrode support structure assembly
US11896330B2 (en) 2019-08-15 2024-02-13 Auris Health, Inc. Robotic medical system having multiple medical instruments

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US5454377A (en) * 1993-10-08 1995-10-03 The Ohio State University Method for measuring the myocardial electrical impedance spectrum
US5447529A (en) * 1994-01-28 1995-09-05 Philadelphia Heart Institute Method of using endocardial impedance for determining electrode-tissue contact, appropriate sites for arrhythmia ablation and tissue heating during ablation

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8160690B2 (en) 2007-06-14 2012-04-17 Hansen Medical, Inc. System and method for determining electrode-tissue contact based on amplitude modulation of sensed signal
US8489184B2 (en) 2007-06-14 2013-07-16 Hansen Medical, Inc. System and method for determining electrode-tissue contact based on amplitude modulation of sensed signal
US9918653B2 (en) 2009-01-15 2018-03-20 Koninklijke Philips Electronics N.V. Electrophysiology catheter
WO2010082145A3 (fr) * 2009-01-15 2010-09-30 Koninklijke Philips Electronics N.V. Sonde d'électrophysiologie
CN102316794B (zh) * 2009-01-15 2015-06-17 皇家飞利浦电子股份有限公司 电生理学导管
WO2010082145A2 (fr) 2009-01-15 2010-07-22 Koninklijke Philips Electronics N.V. Sonde d'électrophysiologie
CN102316794A (zh) * 2009-01-15 2012-01-11 皇家飞利浦电子股份有限公司 电生理学导管
US10555672B2 (en) 2012-11-19 2020-02-11 Biosense Webster (Israel) Ltd. Using location and force measurements to estimate tissue thickness
US11826172B2 (en) 2014-05-06 2023-11-28 St. Jude Medical, Cardiology Division, Inc. Electrode support structure assembly
CN105078569A (zh) * 2014-05-22 2015-11-25 南京医科大学第一附属医院 交感神经标测消融装置及系统
JP2019501679A (ja) * 2015-10-21 2019-01-24 セント・ジュード・メディカル，カーディオロジー・ディヴィジョン，インコーポレイテッド 高密度電極マッピングカテーテル
US10362954B2 (en) 2015-10-21 2019-07-30 St. Jude Medical, Cardiology Division, Inc. High density electrode mapping catheter
US10595738B2 (en) 2015-10-21 2020-03-24 St. Jude Medical, Cardiology Division, Inc. High density electrode mapping catheter
WO2017070559A1 (fr) * 2015-10-21 2017-04-27 St. Jude, Cardiology Division, Inc. Cathéter de cartographie à électrodes de haute densité
US11642064B2 (en) 2015-10-21 2023-05-09 St. Jude Medical, Cardiology Division, Inc. High density electrode mapping catheter
US11039773B2 (en) 2015-10-21 2021-06-22 St. Jude Medical Cardiology Division, Inc. High density electrode mapping catheter
US11559360B2 (en) 2015-10-30 2023-01-24 Auris Health, Inc. Object removal through a percutaneous suction tube
US11534249B2 (en) 2015-10-30 2022-12-27 Auris Health, Inc. Process for percutaneous operations
US11382650B2 (en) 2015-10-30 2022-07-12 Auris Health, Inc. Object capture with a basket
US11571229B2 (en) 2015-10-30 2023-02-07 Auris Health, Inc. Basket apparatus
US11540876B2 (en) 2016-05-03 2023-01-03 St. Jude Medical Cardiology Division, Inc. Irrigated high density electrode catheter
US11433220B2 (en) 2017-07-07 2022-09-06 St. Jude Medical, Cardiology Division, Inc. Layered high density electrode mapping catheter
US11642063B2 (en) 2018-08-23 2023-05-09 St. Jude Medical, Cardiology Division, Inc. Curved high density electrode mapping catheter
EP3682832A1 (fr) * 2018-12-28 2020-07-22 Biosense Webster (Israel) Ltd. Réglage de phases d'un générateur d'ablation à phases multiples pour détecter un contact
JP2020108775A (ja) * 2018-12-28 2020-07-16 バイオセンス・ウエブスター・（イスラエル）・リミテッドＢｉｏｓｅｎｓｅ Ｗｅｂｓｔｅｒ （Ｉｓｒａｅｌ）， Ｌｔｄ． 接触を検出するための多相アブレーション発生器の位相の調整
US11826088B2 (en) 2018-12-28 2023-11-28 Biosense Webster (Israel) Ltd. Adjusting phases of multiphase ablation generator to detect contact
JP7391660B2 (ja) 2018-12-28 2023-12-05 バイオセンス・ウエブスター・（イスラエル）・リミテッド 接触を検出するための多相アブレーション発生器の位相の調整
US11896330B2 (en) 2019-08-15 2024-02-13 Auris Health, Inc. Robotic medical system having multiple medical instruments
US11439419B2 (en) 2019-12-31 2022-09-13 Auris Health, Inc. Advanced basket drive mode

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