Ablation catheter positioning system
First Claim
1. A system for detecting the relative disposition of a catheter assembly inserted along a vessel of a patient, wherein the catheter has a plurality of electrodes spaced successively along its length, such system comprisingsignal applying means adapted to be coupled to said catheter assembly for applying a sensing signal for propagation through tissue extending in a region located about a first pair of electrodes and about a second pair of electrodes which are disposed along said catheter, to produce a sensing output of each pair of electrodes corresponding to a measure of tissue impedance pathways between the electrodes of such pair, andmeans for differently combining the sensing output simultaneously produced by each of the two electrode pairs into a single differential signal indicative of the disposition of said catheter in said vessel with respect to adjacent tissue.
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Accused Products
Abstract
A multi-electrode cardiac catheter has pairs of electrodes connected to sensing circuitry to produce a differential signal. The sensing output is sharply defined and self-normalizing. Preferably a catheter ablation tip electrode is an electrode of one pair, and the differential signal becomes non-zero when the tip contacts surrounding tissue. The shape of the differential signal provides information on the degree of electrode contact, as well as on the on the amount of locally-sensed tissue impedance change. The signal may be used as a trigger enable signal for a cardiac ablation catheter, and the applied level of RF power may be controlled based on the indicated degree of electrode contact and value of tissue impedance.
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Citations
13 Claims
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1. A system for detecting the relative disposition of a catheter assembly inserted along a vessel of a patient, wherein the catheter has a plurality of electrodes spaced successively along its length, such system comprising
signal applying means adapted to be coupled to said catheter assembly for applying a sensing signal for propagation through tissue extending in a region located about a first pair of electrodes and about a second pair of electrodes which are disposed along said catheter, to produce a sensing output of each pair of electrodes corresponding to a measure of tissue impedance pathways between the electrodes of such pair, and means for differently combining the sensing output simultaneously produced by each of the two electrode pairs into a single differential signal indicative of the disposition of said catheter in said vessel with respect to adjacent tissue.
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11. A system for detecting the relative disposition of a multi-electrode catheter assembly inserted along a vessel of a patient, such system comprising
signal applying means adapted to be coupled to said catheter assembly for applying a sensing signal for propagation through tissue extending adjacent to both a first electrode pair and to a second electrode pair, each disposed along said multi-electrode catheter, so as to produce first and second sensing outputs across said first and said second electrode pair, respectively, each sensing output corresponding to a measure of local tissue impedance pathways between electrodes of such pair. means for combining the sensing output simultaneously produced by each of the two electrode pairs into a signal differential signal, said combining means including a first amplifier and a second amplifier for amplifying the sensing output of said first and said second electrode pairs, respectively, and at least one of said amplifiers has a gain selected to produce a normalized signal such that both amplifiers produce outputs of equal magnitude when said first and second electrode pairs are immersed in blood, said combining means combining the outputs of both said first and said second amplifiers into said differential signal so that the differential signal is normally null and varies in accordance with the differences between tissue located immediately adjacent said first electrical pair and tissue located immediately adjacent said second electrode pair.
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13. A catheter positioning system, for a mapping catheter having a plurality of at least three electrodes disposed in an ordered sequence along a segment of the catheter, with conductors extending from the catheter for selectively connecting the electrodes to the system, such system comprising
a signal source for providing a signal means for connecting said signal source between two electrodes of said plurality of electrodes, the two electrodes including a least one electrode located at an end of the segment so that the signal propagates through tissue surrounding the catheter, and the tissue forms an impedance-dividing bridge producing detectable signals across each pair of the electrodes disposed along the segment due to propagation of the signal along impedance pathways through tissue adjoining the mapping catheter means for forming a differential signal by combining the detectable signals produced across each of two pairs of electrodes of said multi-electrode catheter, wherein the two pairs of said electrodes include at least one electrode located between ends of the segment, and means for evaluating the differential signal to determine catheter position.
Specification