# US 2014/0155722 A1 · Catheter systems for measuring electrical properties of tissue and methods of use > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155722 A1 - Document ID: US20140155722A1 - Status: Published application - Kind: A1 - Application number: 14/091,423 - Filed: 2013-11-27 - Published: 2014-06-05 - Earliest claimed: 2012-11-29 - Assignees: Albert Einstein Healthcare Network - Applicants: The Trustees of the University of Pennsylvania; Albert Einstein Healthcare Network - Inventors: Allan M. Greenspan; Yale E. Goldman - Web page: https://patentgrep.com/patent/US20140155722A1 ## CPC - A61B 5/0538: invasively, e.g. using a catheter - A61B 5/283: Invasive - A61B 5/6852: {Catheters} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract Catheter systems for measuring at least one electrical property, e.g., impedance, of cardiac tissue of a living being are disclosed. The system includes a catheter having a tip with a sensing electrode, a guard electrode and an electrical shield. The sensing electrode is arranged to engage the cardiac tissue and is coupled to circuitry for measuring the at least one electrical property of the cardiac tissue, shielding the sensing electrode from bulk blood adjacent the cardiac tissue. The measurement can gated to the cardiac cycle. Additional embodiments include multi-electrode sensor catheter tips for high density mapping. Moreover, such tips may be dynamically configurable, i.e., their electrodes can be variably assigned as sensor electrodes or guard electrodes by associated circuitry. Such multi-electrode configuration and reconfiguration can be gated to the cardiac cycle. ## Claims ### Claim 1 A catheter for introduction into the body of a living being for measuring at least one electrical property of cardiac tissue of the being, said catheter having a distal end comprising a sensing electrode, a guard electrode and an electrical shield, said sensing electrode being arranged to engage the cardiac tissue and coupled to circuitry for measuring the at least one electrical property of the cardiac tissue, said guard electrode surrounding said sensing electrode and being arranged for engaging said cardiac tissue and shielding said sensing electrode from bulk blood adjacent the cardiac tissue, said electrical shield surrounding said guard electrode. ### Claim 2 (depends on 1) A system comprising the catheter of claim 1 and a follower amplifier and wherein a voltage appears at said sensing electrode, said follower amplifier being arranged to apply a signal to said guard electrode to maintain the potential of said guard electrode at the same voltage as the voltage appearing at said sensing electrode. ### Claim 3 (depends on 1) A system comprising the catheter of claim 1 and electronic control circuitry and wherein said sensing electrode comprises at least one of a plurality of electrodes, and said guard electrode comprises another subset of said plurality of electrodes, said control circuitry being coupled to said plurality of electrodes for selecting which of said plurality of electrodes shall form said at least one sensing electrode and which of said plurality of electrodes shall form said subset of said plurality of electrodes forming said guard electrode. ### Claim 4 (depends on 3) The system of claim 3 comprising a follower amplifier and wherein a voltage appears at said sensing electrode, said follower amplifier being arranged to apply a signal to said guard electrode to maintain the potential of said guard electrode at the same voltage as the voltage appearing at said sensing electrode. ### Claim 5 (depends on 4) The system of claim 4 wherein said control circuitry is arranged to determine which of said plurality of electrodes are in contact with the cardiac tissue. ### Claim 6 (depends on 3) The system of claim 3 wherein said electrodes measure impedance and wherein said control circuitry determines which of said plurality of electrodes are in contact with the cardiac tissue based upon the impedance measured by said electrodes. ### Claim 7 (depends on 1) A system comprising the catheter of claim 1, wherein said at least one electrical property of the cardiac tissue is impedance, and a signal source, said signal source applying a small, harmless current to said sensing electrode, whereupon a sensed voltage occurs at said sensing electrode that is indicative of impedance of the cardiac tissue in the vicinity of the sensing electrode. ### Claim 8 (depends on 7) The system of claim 7, further comprising a phase demodulator arranged to receive said sensed voltage, wherein said signal source is a time-varying signal and wherein said phase demodulator indicates in-phase and quadrature components of said sensed voltage. ### Claim 9 A catheter system for detecting at least one electrical property of anisotropically conducting cardiac tissue of a living being in an area of the tissue comprising surrounding blood having electrical conductance, said system comprising a catheter having a distal end comprising electrodes and arranged for engaging the cardiac tissue for effecting high density impedance mapping thereof, said distal end of said catheter being arranged to reduce shunt conductance which exists between the electrodes and the surrounding blood. ### Claim 10 (depends on 9) The catheter system of claim 9 wherein said distal end comprises a sensing electrode, a guard electrode and an electrical shield, said sensing electrode being arranged to engage the cardiac tissue and coupled to circuitry for measuring the at least one electrical property of the cardiac tissue, said guard electrode surrounding said sensing electrode and being arranged for engaging said cardiac tissue and shielding said sensing electrode from the surrounding blood adjacent the cardiac tissue, said electrical shield surrounding said guard electrode. ### Claim 11 (depends on 10) The catheter system of claim 10 additionally comprising a follower amplifier and wherein a voltage appears at said sensing electrode, said follower amplifier being arranged to apply a signal to said guard electrode to maintain the potential of said guard electrode at the same voltage as the voltage appearing at said sensing electrode. ### Claim 12 (depends on 10) The catheter system of claim 10 additionally comprising electronic control circuitry and wherein said sensing electrode comprises at least one of a plurality of electrodes, and said guard electrode comprises a subset of said plurality of electrodes, said control circuitry being coupled to said plurality of electrodes for selecting which of said plurality of electrodes shall form said at least one sensing electrode and which of said plurality of electrodes shall form said subset of said plurality of electrodes. ### Claim 13 (depends on 12) The catheter system of claim 12 additionally comprising a follower amplifier and wherein a voltage appears at said sensing electrode, said follower amplifier being arranged to apply a signal to said guard electrode to maintain the potential of said guard electrode at the same voltage as the voltage appearing at said sensing electrode. ### Claim 14 (depends on 13) The catheter system of claim 13 wherein said control circuitry is arranged to determine which of said plurality of electrodes are in contact with the cardiac tissue. ### Claim 15 (depends on 10) The catheter system of claim 10 additionally comprising a signal source, said signal source applying a small current to said sensing electrode, whereupon a sensed voltage occurs at said sensing electrode that is indicative of impedance of the cardiac tissue in the vicinity of the sensing electrode. ### Claim 16 (depends on 9) The system of claim 9 wherein the catheter is limited in size so as to be arranged to measure the impedance at a plurality of points on the cardiac tissue at a density of at least four points/cm2.