Nesiritide Following Maze and Mitral Valve Surgery

BACKGROUND: Fluid retention following "maze" and mitral valve surgery has been associated with diminished levels of atrial natriuretic peptide (ANP). We hypothesized prophylactic administration of nesiritide (human recombinant brain natriuretic peptide, NES, Natrecor, Scios, Fremont, CA, USA), which has similar physiologic properties to ANP and would promote diuresis in maze and mitral patients postoperatively. METHODS: Randomized, blinded, prospective pilot study comparing patients undergoing maze and mitral surgery including excision of the left atrial appendage. Three hours after cardiopulmonary bypass, patients received either a 72-hour infusion of NES at 0.01 mcg/kg/min (n = 9) or placebo (n = 10). Diuresis, diuretics, time to extubation, oxygenation, ANP, and serum Endothelin-1 levels were measured. Nonparametric analysis with Mann-Whitney test was performed with SPSS (SPSS Inc., Chicago, IL, USA). RESULTS: In both groups, postoperative ANP levels fell from baseline (NES 330 to 280 ng/mL and control 220 to 150 ng/mL). There were no significant differences in patients receiving NES compared to controls in diuresis (1.33 mL/kg/hour urine output NES vs. 1.68 mL/kg/hour controls, p = 0.14); furosemide dosage (0.04 mg/kg/hour NES vs. 0.04 mg/kg/hour controls, p = 0.08); time to extubation (17.5 hours NES vs. 19.5 control, p = 0.42) or PaO2/FiO2 ratio at 48 hours (NES 200 vs. 273 control, p > 0.05). Endothelin-1 levels were higher at baseline with NES but not at 1 and 72 hours after cardiopulmonary bypass (NES 3.1, 3.8, 2.9 pg/mL vs. control 1.85, 4.05, 2.75 pg/mL; p = 0.01, 0.77, 0.47). CONCLUSIONS: This pilot study did not demonstrate additional diuresis with nesiritide in postoperative mitral/maze patients already following a loop diuretic protocol.