Safety and Efficacy of Direct Blood Volume Measurement in the Treatment of Heart Failure

Inclusion Criteria: * Age \>21 years * Discharge from hospital or emergency department observation unit with a primary diagnosis of acute decompensated heart failure * Planned discharge home * Able and willing to provide informed consent Exclusion Criteria: * Significant co-morbidity during heart failure hospitalization (treated pneumonia, sepsis, respiratory failure, oliguric renal failure, major bleeding requiring transfusion, stroke) * Heart failure primarily due to significant valvular disease, sub-aortic outflow obstruction, active myocardial ischemia, apical ballooning syndrome, active arrhythmias, active myocarditis, primary restrictive cardiomyopathy, pericardial disease, or congenital heart disease * Other major co-morbidities that increase mortality risk (stroke with hemiplegia, diabetes with end-organ damage other than heart disease, history of cancer in last 2 years, moderate to severe liver disease, HIV infection with AIDS) * Hospitalization length of stay \>10 days * Evidence of acute coronary syndrome during qualifying heart failure hospitalization * Planned revascularization procedure within 6 months * Planned implantation of ICD or pacemaker within 6 months * Planned placement on cardiac transplantation list within 6 months * Planned other major cardiac surgery or other surgery within 6 months * Planned intermittent or continuous intravenous positive inotropic therapy * Planned intermittent or continuous intravenous vasodilator therapy * Severe obesity (BMI ≥ 40 kg/m2) or cachexia (BMI ≤18 kg/m2) * Severe chronic kidney disease (estimated GFR\<30 ml/min (Modification of Diet in Renal Disease formula20)) * Hemoglobin \< 10 gm/dl * Non-cardiac primary limitation to exercise (rheumatological, orthopedic, pulmonary, neurological or peripheral vascular disease) * Known history of non-adherence with medications * Psycho-social factors that interfere with ability to adhere to study procedures (dementia, active substance abuse, poorly controlled psychiatric illnesses, inability to travel frequently to the study center) * Pregnant women or nursing mothers * Women of childbearing potential not using adequate birth control methods * Known hypersensitivity to iodine, eggs, or any other component of the Volumex injection kit * History of anaphylaxis * Participation in another heart failure investigational treatment protocol currently or \<30 days