Nesiritide, a recombinant human B-type natriuretic peptide, has been used in conjunction with inotropic agents in the management of low cardiac output and pulmonary hypertension following cardiac surgery. However, its independent effects on intraoperative myocardial protection are unknown. This study was, therefore, undertaken to determine whether nesiritide alone could enhance myocardial protection when given intraoperatively in a porcine model simulating urgent coronary artery bypass graft surgery.