SOME FACTORS AFFECTING INDICATOR DILUTION CURVES IN THE PRESENCE AND ABSENCE OF VALVULAR INCOMPETENCE

Abstract

Dye dilution curves were made in a circulation model constructed to allow measurement of the amount of forward and backflow through an incompetent valve. Variation of the stroke and residual volume of the pump when the valve was competent produced statistically significant but minor changes in the 5 Curve parameters and 2 ratios studied. When the valve was incompetent changes of size, shape, and elasticity of the chamber entered by the regurgitant jet were shown to produce in the dye curves significant and sometimes major changes independent of the amount of backflow. Until these variables can, be measured in man or in a model it is not possible by this technique to measure quantitatively the amount of backflow and it may be difficult to decide whether it is large or small.