Researchers are trying learn more about how the heart and blood volume interact in subjects with heart failure and how measuring blood volume may help them develop better ways of treating and managing heart failure patients.

Inclusion Criteria:

• Acute Decompensated Chronic Heart Failure, diagnosed clinically with volume overload by the primary Heart Failure provider or Emergency Department physician and admitted to hospital.
• New York Hear Association functional class III-IVa with stage C or D Heart Failure with Left Ventricular Ejection Fraction <50%
• Intended treatment plan with intravenous loop diuretic therapy during hospitalization
• Meeting none of the Exclusion Criteria

Exclusion Criteria:

• Age < 18 years
• Having received any investigational drug or device within 30 days prior to entry into the study.
• Clinically unstable patients (e.g. systolic blood pressure < 90 mmHg, ongoing requirement for vasopressors or mechanical circulatory support, or mechanical ventilation).
• Hospitalization within three months prior to study for hemodialysis or an ongoing requirement for hemodialysis or ultrafiltration.
• Prior organ transplantation or being on a waiting list for organ transplantation
• Presence of cardiac conditions such as clinically significant cardiac valve stenosis, hypertrophic cardiomyopathy, restrictive cardiomyopathy, constrictive pericarditis, or primary arterial pulmonary hypertension (Group 1 PAH).
• History of blood pressure > 190/115 mmHg or unexplained syncope within the past 3 months.
• Symptomatic carotid artery disease, known critical carotid stenosis, or stroke within the past 3 months
• Clinically significant intrinsic renal disease (eGFR <15 ml/min/1.72m2), renal artery stenosis, or history of fibromuscular dysplasia of the renal arteries
• Baseline hemoglobin < 8.5 g/dl, aspartate aminotransferase (AST) or alanine aminotransferase (ALT) that is five times or more the upper limit of normal or bilirubin three times or more the upper limit of normal
• History of alcohol abuse within the past 6 months.