The aims of this study were i) to develop an innovative procedure combining micro-extraction by packed sorbent (MEPS) with ultra-high-performance liquid chromatography coupled to electrospray ionization triple-quadrupole mass spectrometry (UHPLC-ESI-MS/MS) for the simultaneous determination of 8-isoprostaglandin F2α (8-isoPGF2α) and cortisol in saliva and ii) to monitor lactate, uric acid, TNF-α, cortisol, α-amylase and 8-isoPGF2α concentrations in stimulated saliva samples collected from 44 HF patients during their hospital stay due to acute HF. The gene discussed is TNF; the disease is hydrops fetalis.