Assessment of Mitral Regurgitation by Dye Dilution Curves

Hering (1829, 1832) obtained circulation times by detecting injected samples of potassium ferrocyanide by the Prussian Blue reaction, as quoted by Dow (1956). Stewart (1894) extended the work of Hering and was able to measure the cardiac output by a quantitative determination of the dilution of a solution of salt injected intravenously. It has taken many years since Stewart's time for the indicator dilution technique to become clinically accepted, and this is but an indication of the many problems that had first to be solved, not least amongst which has been the improvement of recording devices. This paper deals with the assessment of mitral regurgitation by the indirect indicator technique with special reference to the Shillingford Index (Shillingford, 1958). Coomassie Blue was chosen as the indicator. The properties, biological behaviour and clinical applications of this blue azo dye have been fully dealt with by Taylor and Thorp (1959) and Taylor and Shillingford (1959), who found it eminently suitable as an indicator dilution substance. The dye is relatively non-toxic and does not cause staining of the skin. It can be extracted readily by the urea and acetone method of Clausen and Lifson (1956). The dye remains wholly intravascular by being bound to the serum proteins, is metabolized by reductive fission of the azo link, and is