Comparing the Effects of Conivaptan and Diuretics on Plasma Neurohormones and Renal Blood Flow in Patients With Chronic Congestive Heart Failure

Inclusion Criteria:

Have a diagnosis of chronic congestive heart failure of any etiology
Be between 18-80 years of age
Able to provide consent
Have a documented left ventricular ejection fraction within the last year of < 40%
On a stable dose (no changes within 2 weeks) of 40 mg or greater daily dose of furosemide or its equivalent
On standard HF therapy medications (ACEI or ARB and beta-blocker unless contraindicated)
Have an estimated glomerular filtration rate (GFR) of 30 ml/minute or greater (based on the Cockcroft Gault calculation)
Have a hemoglobin of > 10 grams/dl
Have a negative urine pregnancy for women of childbearing years only

Exclusion Criteria:

Acute coronary syndrome within 1 month
Systolic blood pressure less than or equal to 90 mmHg at time of enrollment
Poor peripheral venous access
Severe concomitant disease which deemed by the investigator would render them unsuitable for this trial
Allergy or contraindication to the use of iothalamate, PAH - Specifically any allergies to iodine or iodine containing products, history of asthma and hay fever which deemed by the investigator would render them unsuitable for this trial