We hypothesize that nesiritide will have favorable effect in decreasing heart filling pressures and echocardiogram studies.

In previous studies, patients with systolic heart failure were given nesiritide and had reduced heart filling pressures. The FDA has approved nesiritide for these patients.

Between one-third and one-half of patients with heart failure have diastolic heart failure. Few of these patients have been studied while receiving nesiritide.

A study is needed to test nesiritide on this specific type of heart failure.

Patients will undergo a heart catheterization and heart biopsy. Patients will then be transferred to the intensive care unit for monitoring. An echocardiogram will be obtained, followed by an infusion of nesiritide for 24 hours. At the completion of the infusion, a repeat echocardiogram will be obtained.

Inclusion Criteria:

Elevated heart filling pressure. Ejection fraction >45%. Blood pressure >90. Physician feels that the patient needs intravenous medication for heart failure.

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Exclusion Criteria:

Patients receiving intravenous medication. Patients with significant heart disease or who are unstable. Patients with kidney failure or severe heart valve disease.

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