TNF and hydrops fetalis: HF - heart failure, ELISA - enzyme-linked immunosorbent assay, LC-MS/MS - liquid chromatography with tandem mass spectrometry, IL - interleukin, TNF - tumor necrosis factor, CRP - C-reactive protein, CE-TOF MS - capillary electrophoresis time of flight mass spectrometer, LAL - limulus amebocyte lysate, ET - endothelin, LVAD - left ventricular assist device, LPS - lipopolysaccharides, HT - heart transplant, TMA-lyase - trimethylamine-lyase, PICRUSt - phylogenetic investigation of communities by reconstruction of unobserved states, HFpEF - heart failure with preserved ejection fraction