INDICATOR DILUTION CURVES IN MITRAL VALVULAR DISEASE

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Abstract
Coomassie blue dye was injected consecutively into the right heart and left atrium of 43 cases of mitral valvular disease free from gross left atrial enlargement. Unslurred ear-piece dilution curves were examined by methods that merely expressed distortion, and by methods that discriminated between the effects of regurgitation and the results of decreased cardiac output and increased heart volume. The severity of regurgitation was independently assessed from the size of the mitral orifice in severely disabled cases. The ratio of least concentration to recirculation peak concentration is the least discriminative of the indices tested, and yet it was the most successful in ranking patients according to the severity of regurgitation. The reason may be that it is affected by all the circulatory abnormalities of clinical mitral regurgitation. Biological and technical impediments to the accurate measurement of regurgitant flow and to the clinical assessment of indicator dilution curves are discussed. An appendix, which may be obtained from the authors, offers a simple method for measuring areas under dilution curves, and analyses the theoretical relation between dilution curve downstroke, flow, and volume. It describes the relationships between the Korner-Shillingford regression equations and the arguments of Hamilton and Newman.