Left ventricular stroke volume by single and dual excitation of conductance catheter in dogs.

The conductance method employs a multielectrode catheter to measure intracavitary electric conductance from which left ventricular volume is estimated. A dual-excitation method introduced by us uses a more homogeneous electric field and thereby should enable more accurate volume estimation. In six anesthetized open-chest dogs we compared stroke volume obtained from electromagnetic flow probes with the conventional single-excitation method and with the new dual-excitation conductance method. Caval occlusion and left atrial hemorrhage were used to obtain a wide range of stroke volumes. The slope of the relation between stroke volume calculated from the flow probes and from the conductance catheter increased significantly (P < 0.001) from 0.635 with single excitation to 0.835 with dual excitation, but the interanimal variability was not reduced. The linearity of the relation was substantially improved.