Pulse Densitometer Indocyanine Green Dilution Curves: A Simple Applicable and Accurate Method for Determination of Cardiac Shunts

Objective. Adequate hemodynamic evaluation is crucial in the management of patients with congenital heart disease. Although non-invasive diagnostic tools have reduced the need for invasive procedures, cardiac catheterization is still mandatory for absolute quantification of pressures, flows and vascular resistances in selected patients. We therefore investigated the feasibility of a new technique, non-invasive pulse densitometry (PD) in patients with intracardiac shunts and compared its results with the established standards: cuvette densitometry (CD) and oximetry (OX). Design. Measurement method comparison study. Outcome measure. In 12 patients with intracardiac shunt, dye dilution curves, using both pulse and cuvette densitometry, were recorded and oximetry was performed. Left-to-right shunt expressed as percentage of pulmonary blood flow Qp, was calculated from dye dilution and oximetry. In 4 patients with atrial septal defect, dye dilution curves were also recorded after closure of the defect with a device. Results. The mean difference +/- SD between the shunt derived from PD and CD was 2.8 +/- 10.0% of Qp, 95% confidence interval -2.5 to 8.2. (Shunt-PD vs. Shunt-CD was 32.3 +/- 23.9% vs. 29.5 +/- 23.9% of Qp resp., n = 16). The mean difference +/- SD between the shunt derived from PD and OX was 0.8 +/- 9.8% of Qp, 95% confidence interval -5.4 to 7.0 (Shunt-PD vs. Shunt-OX was 41.5 +/- 20.3% vs. 40.7 +/- 19.7% of Qp resp., n = 12). Conclusion. Transcutaneous recording of dye dilution curves with a pulse dye densitometer allows easy and accurate quantification of intracardiac left-to-right shunt flows over a wide range in both children and adults with congenital heart diseases.