Validity of Indicator-Dilution Determination of Cardiac Output in Patients with

A PREVIOUS STUDY from this laboratory analyzed the effect of mitral regurgita-tion on the validity of the indicator-dilution determination of cardiac output.1 The poten-tial problem of unrecognized early recircula-tion of indicator particles on the primary indicator time-concentration curve2 3 was discussed. The purpose of this report is to ex-tend these observations to patients with aortic regurgitation. Methods Indicator-dilution curves were recorded from the pulmonary artery and a systemic artery after right atrial injection as previously described. ' A total of 298 separate catheterization studies are included in this report. Each value for pulmo-nary and systemic arterial output represents the mean of two separate determinations; a total of 1,192 dye curves were thus analyzed. The subjects were divided into three groups. The first and second groups are identical to those mentioned earlier. ' The third group included 129 catheterizations in patients with varyin