Inclusion Criteria:

• Patients greater than 18 years of age
• Admission to the ED for congestive heart failure requiring IV diuretics and hospitalization
• Chest X-ray evidence of pulmonary congestion (pleural effusion will not suffice).
• Physical evidence of volume overload i.e. rales or edema at time of randomization.
• Normal left ventricular ejection fraction (EF >50%) on echocardiography after presentation to the ER.
• Patients must be able to provide informed consent.

Exclusion Criteria:

• Acute coronary syndrome with evidence of active ischemia as evident by acute ST segment or T wave changes or initial cardiac enzymes that demonstrate myocardial necrosis or requiring IV nitroglycerin for treatment.
• Hemodynamically unstable patients that require invasive monitoring or mechanical ventilation.
• Cardiogenic shock, volume depletion, or any other clinical condition that would contraindicate the administration of IV diuretics, ACE inhibitors, or an IV agent with potent vasodilating properties.
• Systolic blood pressure >220mmHg or diastolic blood pressure >110mHg.
• Systolic blood pressure consistently <90 mmHg.
• Tachyarrhythmia (HR>120).
• Bradyarrythmia (HR < 50).
• Myocarditis.
• Hypertrophic obstructive cardiomyopathy.
• Restrictive or infiltrative cardiomyopathy including amyloid or sarcoid.
• Constrictive cardiomyopathy.
• Primary right sided heart failure or severe pulmonary hypertension (pulmonary artery pressure > 60mmHg).
• Significant aortic or mitral valve stenosis (Aortic Valve Area < 1.0cm2, Mitral Valve Area < 1.5 cm2
• Aortic or mitral insufficiency ≥ 3+.
• Malfunctioning artificial valve.
• Uncorrected congenital heart disease.
• Concomitant administration of IV Dobutamine, or other IV vasoactive medications from 2 hours before the start of the study drug until 3 hours after the start of the study drug;
• Administration of IV Nitroglycerin or IV Milrinone.
• Concomitant administration of oral ACE inhibitor medication from 2 hours before the start of the study drug until 30 minutes after the start of the study drug.
• Severe COPD/Asthma as assessed by clinical criteria, prior PFT's or if the patient requires chronic oral steroid treatment.
• Other significant pulmonary disease that causes significant SOB/DOE i.e. pneumoconiosis etc.
• Patients with creatinine > 3.0 mg/dl.
• Patients with a serum potassium level < 3.5, >5.5 mmol/l.
• Anemia with a Hob < 9 g/dl.
• Acute neurological event.
• Known allergic reaction or contraindication to Natrecor or furosemide.
• Pregnancy or suspected pregnancy.
• Patients with a history of ETOH abuse or other illicit drug abuse.
• Patients with active liver, hematologic, gastrointestinal, immunologic, endocrine, metabolic, central nervous system or other medical condition disease which in the opinion of the investigator may adversely effect the safety and efficacy of the study drug or the lifespan of the patient.
• Therapy with an investigational drug.
• Unwillingness or inability to comply with study requirements including the 30-day follow-up period.