BACKGROUND: Intraoperative fluid management should be aimed at maintaining appropriate left-sided filling pressures. The pulmonary capillary wedge pressure (PCWP) will overestimate the left ventricular end-diastolic volume (LVEDV) when ventricular compliance is markedly reduced in patients with aortic stenosis. Intraoperative transesophageal echocardiography (TEE) is useful for monitoring global left ventricular function and change of preload. This study was undertaken to evaluate preload derived by conventional invasive monitoring technique compare with preload obtained simultaneously from TEE in patients with aortic stenosis. METHODS: Fifteen patients with aortic stenosis who underwent aortic valve replacement were examined. The preload was examined by the short axis view of left ventricle with TEE at the level of the papillary muscles. For each patient, simultaneous measurements of PCWP, thermodilution cardiac output and left ventricular end-diastolic area (LVEDA) measured by TEE were made after the induction of anesthesia and after surgery. RESULTS: The correlation between echo-derived LVEDA and thermodilution cardiac index (CI) (r=0.53, p<0.05) or stroke index (SI) (r=0.56, p<0.05) was good after surgery, but the correlation was not found after induction of anesthesia. No correlation was observed between PCWP and CI or SI. CONCLUSIONS: The PCWP did not provide a reliable estimate of preload and did not allow good prediction of cardiac index. These findings demonstrate that, in patients with aortic stenosis who underwent aortic valve replacement, TEE provides a better index of left ventricular preload than conventional invasive hemodynamic monitoring particularly after surgery.