 In an ongoing prospective study, we are assessing the neurohumoral and renal hemodynamic profile of hospitalized patients with ADHF who do or do not develop the CRS. Our preliminary findings suggest that indeed the combination of pronounced activation of renin-angiotensin-aldosterone system RAAS, decreased renal perfusion pressure and importantly, a relative deficiency of the natriuretic peptides despite marked volume overload predisposes to the development of CRS. 