Use of BNP (nesiritide) vs placebo to help protect kidney function in patients undergoing heart bypass surgery.

This is a randomized, double-blind, placebo controlled study of low dose nesiritide to prevent renal insufficiency after cardiopulmonary bypass surgery. Patients included are those with greater than mild renal insufficiency preoperatively as defined by having a creatinine clearance of less than 50 mL/minute determined by the Cockroft-Gault formula. The infusion of nesiritide (BNP) 0.005 mcg/Kg/minute or placebo begins 1 hour before surgery and runs for 24 hours started after the induction of anesthesia prior to cardiopulmonary bypass.

Inclusion Criteria:

• Patients > 18 years old, undergoing cardiac surgery requiring cardiopulmonary bypass with baseline creatinine clearance < 50 ml/min and who are not dialysis dependent.

Exclusion criteria:

• Cardiogenic shock or hypotension with systolic BP < 90 mmHg.
• Patients with acute or chronic aortic dissection.
• Patients who are enrolled in other studies that have an effect the renal function.