Use of indicator dilution techniques in measuring combined aortic and mitral insufficiency.

• When aortic and mitral valvular insufficiency are present in the same patient, indicator injected into the aortic root regurgitates into the left ventricle and thence into the left atrium. The purpose of this paper is to describe the indicator distribution in such patients and to compare the relationships found with those predicted from a theoretical model of bivalvular insufficiency. Indicator distribution across a single incompetent valve may be extrapolated to the case of two incompetent valves in series. Using the fundamental relationship: flow X concentration X time = units of indicator moved, the ratios of the areas of indicator dilution curves that will be inscribed in the several chambers after injection into the aortic root can be derived. It has been shown for two chambers when indicator is introduced into the chamber immediately distal to the regurgitant valve: