Oximetrically recorded T-1824 dye curves offer a relatively reliable means of identifying the site and type of intracardiac and aortic-pulmonary shunts. The most valid indication of the presence of venoarterial admixture is a shortened appearance time (AT). Curves due to left-to-right shunts can be identified by the presence of a normal appearance time and a prolonged descending slope to which disappearance time (DT) is a good index. The use of ratios between certain time intervals obtained from the curves is of questionable value for the identification of the type of shunt present. Double-peaked dye curves usually, but not always, indicate venoarterial admixture but are not as frequently encountered in patients with such shunts as are shortened appearance times. Comparison of oximetric dye curves and those obtained by serial arterial sampling in normal subjects discloses that the former are quantitatively reliable both as to time intervals and as to the area enclosed, provided 10 mg. or more of dye is injected.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine