Estimation of Ventricular Volumes by a Constant Infusion Indicator Dilution Technique.

• The sudden injection indicator dilution method for the estimation of ventricular volumes J has been applied both in the experimental animal ~ and in man.This method presupposes effective uniform distribution of indicator in each end diastolic volume (EDV), a circumstance which may not occur. Further, it has not yet been practical to evaluate in vivo the possible effects of "nonmixing" on the accuracy of the method. A constant infusion indicator dilution method of measuring ventricular volume offers, at least theoretically, an approach to these problems. It may shed new light on an aspect which is basic to the behavior of injected indicator, i.e., the nature of exchange among the three compartments of a ventricle. These are the diastolic venous return, the end systolic volume (£SV), and the stroke volume (SV). The purposes of this report are to give the background for such an approach and to show that this hitherto undescribed method is feasible and has promise.