Left (LV) and right ventricular (RV) myocardial tissue specimens of end-stage heart failure (HF) patients without (n = 24) and with MCS (n = 39; 594 ± 57 days) were analyzed for cytokine mRNA expression level of IL-1B, interleukin 1 receptor 1/2 (IL-1R1/2), interleukin 1 receptor-like 1 (IL-1RL1), IL-33 and interleukin-1 receptor accessory protein (IL-1RaP). The gene discussed is IL1RAP; the disease is hydrops fetalis.