The krypton85 inhalation test for the detection of left-to-right shunts.

One of the primary reasons for performing cardiac catheterization in patients known to have, or suspected of having, congenital heart disease is to determine whether a left-to-right shunt is present and the site at which it enters the right side of the heart. Although a variety of techniques for the detection of such shunts has been developed (Wood et al., 1957, 1958; Zimmerman, 1959; Braunwald and Morrow, 1960) relatively little specific information regarding their reliability has been published. The inhalation of an inert foreign gas and the determination of its concentration in blood sampled from the right side of the heart and the systemic arterial bed forms the basis of a sensitive test for the determination of left-to-right circulatory shunts (Morrow et al., 1958; Sanders et al., 1959; Braunwald et al., 1960). Radioactive krypton (Kr85) has been found to provide substantial advantages over other gases and it has therefore been employed routinely in this laboratory for the past several years (Sanders and Morrow, 1959; Braunwald et al., 1960). It is the purpose of this communication to analyse the results obtained from the application of the Kr85 inhalation test in 323 patients, in all of whom the specific cardiac diagnosis was subsequently established. In this analysis particular emphasis was placed upon: (1) an evaluation of the reliability of the Kr85 inhalation test in the detection of left-to-right shunts, (2) the establishment of specific criteria for the interpretation of the results of the test, (3) an evaluation of the ability of the test to localize the site of entry of a left-to-right shunt, and (4) the usefulness of the test in detecting multiple left-to-right shunts.