REN and hydrops fetalis: In addition, neurohormonal systems that are active in HF patients to balance the actions of the vasoconstricting neurohormones comprise natriuretic peptides (NPs) (Table 1) released in response to increased atrial and myocardial stretch, unloading the heart by enhancing the renal excretion of salt and water and blocking the release of renin and aldosterone [50].