Estimating left ventricular offset volume using dual-frequency conductance catheters.
The measurement of left ventricular volume by the conductance-catheter technique has many advantages, but it is difficult to determine absolute volumes with this method. Current procedure requires that a bolus of concentrated hypertonic saline be injected to measure absolute volume. It also demands that the subject be in a steady state and that measurements only be made at discrete intervals. The saline bolus may affect the cardiovascular state of the subject. This paper describes a new technique for estimating absolute volume utilizing the conductance catheter that relies on the different frequency responses of blood and muscle. Good correlation between the salt-injection method and the dual-frequency method was found in nine closed-chest pigs anesthetized with pentobarbital sodium (r = 0.922). Further refinements may extend the utility of the dual-frequency approach.
Gawne
T J
TJ
Uniformed Services University of the Health Sciences, Department of Medicine, Bethesda, Maryland 20814.
Gray
K S
KS
Goldstein
R E
RE
D000818:Animals; D001810:Blood Volume; D002404:Catheterization; D004553:Electric Conductivity; D004594:Electrophysiology / Q000295:instrumentation*; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles; D013318:Stroke Volume; D013552:Swine; D013599:Systole