Participants in this study will begin study procedures within the first 24 hours of their hospital admission for heart failure. Participants will be randomly assigned to receive one of the following four treatments: high dose furosemide via continuous intravenous (IV) infusion and placebo every 12 hours via IV bolus; low dose furosemide via continuous IV infusion and placebo every 12 hours via IV bolus; high dose furosemide every 12 hours via IV bolus and placebo via continuous IV infusion; and low dose furosemide every 12 hours via IV bolus and placebo via continuous IV infusion. Each participant will receive treatment for the first 72 hours of his or her hospital stay. Participants will answer questionnaires and undergo physical examinations and blood tests during the first 96 hours of hospitalization and again before hospital discharge or on Day 7, if that occurs first. Participants will be asked to return to their doctors 60 days following hospital discharge to evaluate their responses to treatment.