This study will assess the renal hemodynamic effect of RLX030 infusion in subjects with chronic heart failure. In addition safety and effects on renal function and biomarkers will be assessed.

Inclusion Criteria:

• Written informed consent must be obtained before any assessment is performed.
• Male and female heart failure patients with body weight <160 kg, on standard therapy including a stable dose of furosemide 40-240 mg/day orally (p.o). or equivalent dose of loop diuretics, reduced systolic function (LVEF ≤ 45% measured within the past 6 months), BNP ≥ 100 pg/mL or NT-pro-BNP of ≥ 400 pg/mLNYHA Class II or III, and worsening symptoms, e.g. fatigue, dyspnea, breathlessness within 3 months
• Mild to moderate renal impairment

Exclusion criteria:

• Systolic blood pressure (SBP) < 110 mm Hg at the time of randomization
• Administration of intravenous radiographic contrast agent within 72 hours prior to randomization or acute contrast-induced nephropathy at the time of randomization
• Current use of non-steroidal antiinflammatory drugs (NSAIDs)
• Current or planned (through the completion of study drug infusion) treatment with any i.v. therapies, including vasodilators (including nesiritide), positive inotropic agents, vasopressors, levosimendan, or mechanical support (intra-aortic balloon pump, endotracheal intubation, mechanical ventilation, or any ventricular assist device).
• Clinically significant hepatic impairment defined as hepatic encephalopathy of any degree or total bilirubin > 50 μmol/l (3 mg/dl) or, if patient is not on warfarin therapy, INR > 2.0 (or Prothrombin Time > 2 * ULN)

Other protocol-defined inclusion/exclusion criteria may apply.