This is a randomized, double-blind, placebo-controlled, dose ranging pilot study to examine the effects of conivaptan in patients with acute decompensated heart failure.

Inclusion Criteria:

• Patients may be male or female age 18 years or older.
• Women must be post-menopausal or surgically sterile.
• Patients must have chronic heart failure of at least 2 months duration and be hospitalized for the treatment of worsening heart failure. The primary manifestation of worsening heart failure must be worsening dyspnea.