Diltiazem may preserve renal tubular integrity after cardiac surgery

Purpose: To evaluate the influence of dopamine and diltiazem on renal function and markers for acute renal failure, including urinary alpha-glutathion s-transferase (alpha-GST), alpha-1-microglobulin (alpha(1)-MG) and N-acetyl-beta-glucosaminidase (B-NAG) after extracorporeal circulation. Methods: In a randomized, placebo-controlled, double-blind trial we evaluated the efficacy of dopamine (2.5 mug.kg(-1).min(-1)), diltiazem (2 mug.kg(-1).min(-1v)) or placebo administered over 48 hr postoperatively to maintain renal tubular integrity in 60 elective cardiac surgery patients. alpha-GST, alpha(1)-MG, beta-NAG, and creatinine clearance were measured from urine collected during surgery (T0), the first four hours (T1), 24 hr (T2) and 48 hr (T3) postoperatively. Results: Cumulative urine output in the diltiazem group (9.0 +/- 2.8 L) increased significantly compared with placebo (7.0 +/- 1.6 L), but not compared with dopamine (7.8 +/- 1.8 L). Creatinine clearance no significant intergroup differences. In all groups alpha(1)-MG increased from T0 to T3, but we found no significant intergroup differences. alpha-GST increased significantly from T0 to T3 in the placebo (2.1 +/- 1.8 to 11.4 +/- 8.6 mug.L-1) and in the dopamine groups (2.7 +/- 1.8 to 13.6 +/- 14.9 mug.L-1), but not in the diltiazem group (1.8 +/- 1.4 to 3.2 +/- 3.2 mug.L-1). Forty-eight hours postoperatively alpha-GST was significantly lower in the diltiazem group than in both other groups. Conclusions: Diltiazem stimulates urine output, reduces excretion of alpha-GST and beta-NAG and may be useful to maintain tubular integrity after cardiac surgery.