Some theoretical aspects of quantification of mitral valve regurgitation by the indicator-dilution method; sufficient and insufficient experiments.

I curves have been used in the past for the determination of cardiac output," measurement of so-called cardiopulmonary or central blood volume," detection of intracardiac shunts," and, more recently, in an attempt to quantify valvular insufficiency." Despite the extensive literature which has accumulated and which has been recently reviewed by Dow, a complete, theoretical analysis of the indicator output from a two-chamber pulsatile heart is lacking. Analysis of a more simple system, namely, a single pulsatile chamber, has been made by Xewman et al. and Holt. To meet this need for an analysis of the indicator output of a two-chamber pulsatile heart, both in the presence and absence of valvular regurgitation, we have undertaken to study the behavior of a mathematical model simulating action of the heart. At a time when this work was almost complete, McClure, Lacy, Latimer, and Newman published a partial analysis of the performance of a similar model. Although the overall conclusions were generally the same, there were certain dissimilarities in the method of approach between the development published by these authors and our own study. Furthermore, our more complete analysis has led us to certain striking conclusions regarding the use of indicator-dilution curves for quantifying regurgitation.