Sato M, et al. - In this prospective cohort study, researchers examined the accuracy of arterial waveform analysis estimations of cardiac output (CO_AW) and the efficacy of calibrations involving transesophageal echocardiography with continuous cardiac output values obtained using a pulmonary artery catheter. In this study including patients undergoing aortic valve replacement for aortic stenosis, acceptable trending ability pre-cardiopulmonary bypass (CPB) was demonstrated by CO_AW measurements, using LiDCOrapid. For managing such a patient population, the utility of the determination of cardiac output variations, using transesophageal echocardiography, was shown.