Quantitation of Bidirectional Shunt from A Single Dye-Dilution Curve

概要

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A method for quantitating intracardiac bidirectional shunt and estimating its blood flow is presented. Three curves, defined as "right-to-left shunt curve", "normal pathway curve", and "left-to-right shunt curve" were separately drawn from the original downstream dye-dilution curve, and their areas A", A, A' respectively, were calculated in the conventional manner. A'/A showed left-to-right shunt ratio (Q_<L-R%>) even in the presence of right-to-left shunt. However, right-to-left shunt ratio (Q_<R-L%>) was given by (1-A'/A)/(A/A"+1-A'/A), and equalled A"/(A + A") only when left-to-right shunt was absent (A'= O). A"/(A + A") should become increasingly higher than Q_<R-L%> with rise in Q_<L-R%> (= A'/A). The relationship between A"/(A + A") and Q_<R-L%> for various A"/A isopleths is shown by figure. A good agreement (r = 0.848, p < 0.001) was found between Q_<L-R%> values by the present method and those calculated by the oxygen method. In contrast, Q_<R-L%> values by the present method were consistently lower than those by the oxygen method; the difference was exaggerated especially in cases with history of cardiac failure, and these cases tended to show lower systemic flow. The average difference in Q_<R-L%> between the two methods, found in cases free from failure; was 7 per cent. This was thought to be ascribed to intrapulmonary physiological shunt.
社団法人日本循環器学会の論文
1975-06-20