Overestimation of left ventricular volume by the indicator dilution technique.

• Since the work of Bing and co-workers and the subsequent observations of Holt, the indicator dilution technique has been used to measure ventricular volume. The validity of the technique depends upon thorough mixing of indicator with ventricular blood. However, experimental data have been presented by Irisawa et al. and subsequently by Swan and Beck suggesting that requisite mixing does not occur promptly or reliably in the left ventricle. Moreover, Hallermann et al., comparing volume estimates made sequentially by angiocardiography and by indicator dilution, have shown a systematic overestimation of volume by the indicator dilution technique, and have suggested that the cause was incomplete mixing of indicator with ventricular blood. Despite these reports of incomplete mixing, several experimental studies have been reported which rely upon left ventricular volume measurements performed by indicator dilution."