Noninvasive cardiac evaluation (NICE) of intracardiac shunts using inhaled radioactive carbon dioxide.

A totally new, noninvasive technique is presented for the detection and analysis of left-to-right cardiac shunts. Five millicuries of oxygen 15-labeled carbon dioxide is administered by a single-breath inhalation technique. The resultant lung washout curve accurately reflects the presence or absence of a shunt. The quantitative studies are promising, but the method must be compared with standard techniques in a statistically significant series. This work is in progress.