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

Indicator-dilution determinations of cardiac index were performed in 298 catheterization studies in three groups of patients, many with aortic regurgitation. The absence of physiologically significant differences between the two sampling sites, the pulmonary artery and systemic artery after right atrial injection, demonstrates that even severe aortic regurgitation does not vitiate the indicator-dilution determination of cardiac output after right heart injection and systemic arterial sampling if the downstroke of the primary dilution curve permits a straight-line semilogarithmic extrapolation.