Résumé : Less-invasive monitoring systems, such as pulse contour methods, are increasingly being used to estimate cardiac output (CO). However, alterations in the arterial waveform caused by intraaortic balloon pump counterpulsation may affect the ability of pulse contour algorithms to determine CO. We investigated the reliability of an uncalibrated pulse contour method, the MostCare system, in patients with cardiac failure receiving intraaortic balloon pump counterpulsation by comparing its measurements of CO with those determined by an intermittent thermodilution method.