Measurement of Mitral Regurgitation in Man by the Upstream Sampling Method Using Continuous Indicator Infusions

The upstream sampling method for measuring mitral regurgitation was evaluated in 19 patients during retrograde left ventricular and transseptal left atrial catheterization. Measurements obtained by using continuous infusions of indicator were compared, in all patients, with those obtained by using sudden single injections and, in 14 patients, with semiquantitative estimates by mitral valvulography. The mean values for regurgitant flow, total flow, and the regurgitant fraction did not differ significantly for the two dilution techniques. However, measurements of forward flow following sudden injections into the left ventricle were significantly larger than those following sudden injection into the pulmonary artery, while the latter differed insignificantly from measurements during continuous infusions into the left ventricle. Although neither technique had excellent reproducibility, the continuous-infusion method was clearly superior in this respect. The authors concluded that (1) a single measurement of mitral regurgitation by upstream sampling has a probability of large error, (2) continuous infusions in place of sudden injections give more reliable estimates, but (3) continuous infusion measurements are reliable only for mean values from replicate determinations.