Human B-type Natriuretic Peptide (BNP) (Nesiritide) to Help Heart, Kidney, and Hormonal Functions in Persons With Lower Heart Pumping Function

Inclusion Criteria: * Subjects with an ejection fraction of less than 45% * No clinical signs or symptoms of congestive heart failure * Ability to walk a minimal distance of \> 450 meters on a 6-minute walk. If the subject is not able to walk 450 meters due to pain in hips and knees and not fatigue or shortness of breath, they will still qualify for the protocol. * The subjects will all be on stable doses of an angiotensin converting enzyme (ACE) inhibitor for two weeks prior to the active study date. * Therapy with other vasodilators, beta-receptor antagonists, digoxin and antiarrhythmic medications will be allowed, however, all medications must be at stable doses two weeks prior to the study date. Exclusion criteria: * Myocardial infarction within 3 months of screening * Unstable angina within 14 days of screening, or any evidence of myocardial ischemia * Significant valvular stenosis, hypertrophic, restrictive or obstructive cardiomyopathy, constrictive pericarditis, primary pulmonary hypertension, or biopsy proven active myocarditis * Severe congenital heart diseases * Sustained ventricular tachycardia or ventricular fibrillation within 14 days of screening * Second or third degree heart block without a permanent cardiac pacemaker * Stroke within 3 months of screening, or other evidence of significantly compromised central nervous system (CNS) perfusion * Total bilirubin of \> 1.5 mg/dL or other liver enzymes \>1.5 times the upper limit of normal * Serum creatinine of …