Abstract
Summary and conclusions
Indicator-dilution curves were recorded from dogs with various degrees of acute pulmonary artery constriction. Time requirements for the various parts of the indicator-dilution curve decreased with mild pulmonary artery constriction and increased with more severe reduction in the lumen of the pulmonary artery. Peak concentration decreased with increasing constriction. These changes are consistent with the theoretical considerations of the genesis of indicator-dilution curves and the dynamics of pulmonary artery constriction. It is suggested that the form of the indicator-dilution curve is dependent upon degree of cardiac compensation as well as severity of the constriction. A time concentration index (TCI) was established for the curves. The per cent change in this index from control gives a sigmoid relationship when plotted against per cent reduction in cross-sectional area of the pulmonary artery.
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