Inclusion Criteria:

• Patients admitted to St Mary's Hospital, Mayo Clinic Rochester MN with NYHA class III-IV decompensated CHF with renal dysfunction as Calculated creatinine clearance of equal or less than 60 ml/min but greater than 20 ml/min using the Cockcroft-Gault formula.

Exclusion Criteria:

• Cause of acute renal dysfunction can be reasonably ascribed to factors other than heart failure or its treatment
• Known intrinsic renal diseases or renal artery stenosis of =>50%
• Patients taking Nitrates within the previous 24 hours
• Patients needing emergency coronary revascularization or those who may have rapidly changing cardiac function (i.e. patients with acute myocardial infarction or shock)
• Peritoneal or hemodialysis within 90 days or anticipation that dialysis or ultrafiltration of any form will be required during the study period
• Systolic blood pressure < 90 mmHg or cardiogenic shock.
• Requirement of pressors for maintenance of blood pressure.
• Intra-aortic blood pump use.
• History of significant uncorrected renal artery stenosis as defined by >50% stenosis.
• Severe aortic or mitral stenosis or significant LV outflow tract obstruction. Hgb < 10 mg/dL
• Pregnant or nursing women.
• Contraindication to nesiritide.
• Inability to have NSAID dose held for up to 30 hours, if being treated with these medications.
• Administration of radiocontrast medium within 7 days of enrollment or anticipated use of such agents during the study