The Cleveland Clinic Foundation

Marquette Medical Systems

Peter K Osborn

John H Petre

Balakrishnan Gopakumaran

Paul Schluter

A method of determining cardiac volume including the steps of positioning a catheter in a blood-filled chamber of a patient's heart. The catheter comprises an elongated body having a distal end, a proximal end, a plurality of spaced electrodes arrayed on the outer surface of the catheter and spaced apart a predetermined distance from each other to define a distal electrode, a proximal electrode and a plurality of pairs of adjacent electrodes between the distal and proximal electrodes to define volume segments within the chamber. The method includes the steps of providing a constant alternating current to the distal and proximal electrodes, measuring the potential between pairs of electrodes located between a distal and proximal electrodes while the distal and proximal electrodes are energized with the constant amplitude alternating current; determining a set of correction factors from the measured raw segmental volumes and catheter curvature; and correcting for field non-uniformity by multiplying the raw volumes by the set of correction factors.

Method and apparatus to correct for electric field non-uniformity in

A method of determining cardiac volume including the steps of positioning a catheter output including the steps of positioning a catheter in a blood-filled chamber of a patient's heart. The catheter comprises an elongated body having a distal end, a proximal end and a plurality of spaced apart electrodes arrayed on the outer surface of the catheter. The electrodes are spaced apart a predetermined distance from each other to define a distal electrode, a proximal electrode and a plurality of pairs of adjacent electrodes between the distal and proximal electrodes to define volume segments within the chamber. The method includes the steps of providing a constant alternating current If1 at a first frequency f1 to the distal and proximal electrodes, measuring the potential between pairs of electrodes located between the distal and proximal electrodes while the distal and proximal electrodes are energized with the current If1, providing a constant alternating current If2 at a second frequency f2 to the distal and proximal electrodes, measuring the potential between pairs of electrodes located between the distal and proximal electrodes while the distal and proximal electrodes are energized with the current If2, determining the corrected volume of each volume segment corrected for current leakage from the measured voltages and the fractional change in tissue conductance due to changes in the frequency of the applied current.

Method and apparatus to correct for electric current leakage in

An in vivo apparatus for determining the absolute conductivity of a liquid such as human blood, including the steps of determining a location in a ventricle of a patient's heart at which blood conductivity may be measured effectively, positioning a catheter having a plurality of spaced electrodes in the ventricle such that at least a pair of adjacent electrodes are positioned at the location, applying a current of known magnitude to the adjacent electrodes, measuring the voltage between the adjacent electrodes, and determining the conductivity of the patient's blood from the known current and measured voltage.

Apparatus for determining the conductivity of blood

An in vivo method of determining the conductivity of a liquid such as human blood, including the steps of determining a location in a ventricle of a patient's heart at which blood conductivity may be measured effectively, positioning a catheter having a plurality of spaced electrodes in the ventricle such that at least a pair of adjacent electrodes are positioned at the location, applying a current of known magnitude to the adjacent electrodes, measuring the voltage between the adjacent electrodes, and determining the conductivity of the patient's blood from the known current and measured voltage.

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West Allis, WI, United States of America

Peter K Osborn