Although the activation of these neurohormonal systems preserves CV homeostasis in the beginning of HF and for the short-term, a plethora of studies, both pre-clinical and clinical trials, have demonstrated that the bioactive molecules generated by the activation of these three systems (catecholamines, angiotensin II, aldosterone and AVP) are becoming toxic to the heart at higher levels. Here, AVP is linked to hydrops fetalis.