Patent ID: 8977334
Filing Date: 2015-03-10
Classification: A61B

Abstract:
1. 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 said distal end of said catheter being arranged to reduce shunt conductance which exists between the electrodes and the surrounding blood, said system further comprising control circuitry configured to measure electrical impedance between pairs of said plurality of electrodes or between each of said plurality of electrodes and ground and to determine based on said impedance which of said electrodes are in contact with the cardiac tissue, said control circuitry further configured to connect a first subset of said plurality of electrodes to a sensing circuit, said sensing circuit configured to measure a voltage at at least one electrode of said first subset of said plurality of electrodes, said control circuitry further configured to connect a second subset of said plurality of electrodes as guard electrodes that are connected to a follower amplifier configured to apply a signal to said guard electrodes to maintain the potential of said guard electrodes at the same voltage as the voltage appearing at said at least one sensing electrode, said guard electrodes surrounding said first subset of electrodes and configured to engage said cardiac tissue and shield said first subset of electrodes from the surrounding blood adjacent the cardiac tissue, said electrical shield surrounding said guard electrodes.