Thermodilution measurement of the right ventricular ejection fraction

This study addressed the clinical reproducibility and validity of the thermodilution (TD) measurement of the right ventricular ejection fraction (RVEF). Forty-one patients underwent right heart catheterization, including TD RVEF, within 2 h of gated first pass (GFP) and gated blood pool (GBP) radionuclide ventriculography; 21 had single plane contrast right ventricular angiography (ANGIO) during the same catheterization. Analysis of variance showed no difference among three successive TD RVEF measurements. (table; see text) Stroke volume by RV ANGIO correlated with Fick (n = 10, r = .86) and thermodilution stroke volume (n = 21, r = .88). It is concluded that although the thermodilution method is an accurate way to measure flow, it is not an accurate way to measure right ventricular ejection fraction, and by inference, ventricular volumes. The most likely explanation for this finding is incomplete mixing as in previous studies of indicator methods of measuring left ventricular volumes.