The patient population recruited for this study will include patients being admitted for acute congestive heart failure. Eligible patients include those who have near normal LV systolic function.

Inclusion Criteria:

• Age 18 to 85 years old
• Admitted with acute heart failure determined by: symptoms of fatigue; shortness of breath; edema; physical evidence of volume overload; and/or pulmonary edema by CXR
• LVEF > or = 40% on recent (< or = 1 month) echo or MUGA
• NYHA class III or IV on admission
• Baseline systolic blood pressure > 90 mm Hg
• Baseline BNP level > 100 pg/ml
• Able to sign informed consent and return for follow-up assessments

Exclusion Criteria:

• Patients with clinically significant hypotension (defined as a systolic blood pressure (SBP) <90 mm Hg)
• Active infection/sepsis as defined by fever > 101.5 F, currently on IV antibiotics
• Creatinine greater than 3.0 mg/dl
• LV ejection fraction < 40% (must be done within the last 30 days prior to signing consent)
• Significant valvular disease or constrictive cardiomyopathy
• Severe Thrombocytopenia (as defined by platelets less than 20,000) or INR > 1.6
• Hypersensitivity to nesiritide or any of its components.
• Pulmonary capillary wedge pressure (PCWP) <16 mmHg
• If patient is of child-bearing age, a pregnancy test will be performed, and the patient is excluded if pregnancy test is positive.