The use of pulsatile perfusion (PP) instead of Non-Pulsatile Perfusion (NP) during cardiopulmonary bypass (CPB) continues to be a source of debate. The disagreements among the conclusions of the published studies may be due to different factors: differences in the type of patients included in the studies, differences in the protocol of the studies and difficulty to quantify the pulsatility of the flow. In the present paper, we propose a quantitative evaluation of Shepard's EEP index, based on the harmonic decomposition of the physiological aortic pressure and flow rate signal. It is thus demonstrated that the surplus energy provided by pulsatile flow remains moderate (of order 10 mmHg), but that it can be improved by changing the relative shapes of the pressure and flow waves.