EDN1 and hydrops fetalis: Indeed, different changes in ET-1-induced RAAS activation occur during the initial development of chronic HF, where the ET-1/ETA axis increased blood pressure and induced RAAS downregulation attenuated by the sympathetic nervous system, and during the progression of HF, where RAAS activation could be induced by the same ET-1/ETA axis due to the cardiac output decrease [187,188].