The study will evaluate the safety and efficacy of intravenous infusion of carperitide using pressure measurements inside the heart and great vessels and measuring carperitide concentration in the blood.

Inclusion Criteria:

• Is hospitalized with congestive heart failure (CHF)
• Has a Swan-Ganz catheter inserted for CHF management and has pulmonary capillary wedge pressure 18 mmHg or higher

Exclusion Criteria:

• Has had a heart transplant
• Requires mechanical ventilation or mechanical circulatory support