Comparison between Radionuclide Ejection Fraction and Fractional Area Changes Derived from Transesophageal Echocardiography Using Automated Border Detection

BACKGROUND: Left ventricular fractional area changes (FAC) can be derived from transesophageal echocardiography using an automated border detection system. However, FAC has not yet been compared to left ventricular ejection fraction (EF) evaluated by a reference technique. The aim of this study was to correlate transesophageal echocardiography automated FAC to EF derived from radionuclide angiography to obtain a quantifying method of global left ventricular systolic function at the bedside. METHODS: Ten critically ill patients, whose lungs were mechanically ventilated, were included in this prospective study. Patients were scheduled for radionuclide EF evaluation when at least 75% of the endocardium was clearly visualized on transesophageal echocardiography. Patients with esophageal pathology or cardiac dysrhythmia were excluded. Ejection fraction derived from radionuclide angiography was measured using technetium 99m. Echocardiographic data were obtained using an ultrasound system with automated border capabilities. Simultaneous measurements of left ventricular EF and FAC were obtained for each patient, both before and after starting a dobutamine intravenous infusion to modify left ventricular contractility. RESULTS: Mean values for radionuclide EF and transesophageal echocardiography FAC were, respectively: 55% +/- 19% (range 19-89%) and 46% +/- 18% (range 17-80%). Left ventricular EF and FAC were significantly correlated (r = 0.85, SEE = 9.6%). Variations of EF and FAC, induced by dobutamine, were also correlated (r = 0.70, SEE = 4.9%). CONCLUSIONS: Fractional area changes determined by transesophageal echocardiography using automated border detection correlate well with radionuclide EF and may be used at the bedside to quantify left ventricular function in selected intensive care unit patients.