Off-pump versus on-pump coronary artery bypass grafting: oxidative stress and renal function.
OBJECTIVE
Oxidative stress and renal dysfunction occur in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (on-pump CABG). Whether the same adverse effects also occur during off-pump CABG is the question in this study.


METHODS
Forty patients, 27 men and 13 women, undergoing elective CABG were included; 20 patients underwent on-pump CABG and 20 patients underwent off-pump CABG. Renal and ischemia/reperfusion injury parameters were studied, as well as malondialdehyde as a parameter for oxidative stress.


RESULTS
The renal function measured as the mean urinary creatinine excretion decreased significantly during surgery for the on-pump CABG group from 7.62+/-4.74 before surgery to 3.07+/-1.49 mmol/l after surgery, whereas no changes occurred in the off-pump CABG group. The mean urinary concentrations of hypoxanthine, xanthine and malondialdehyde expressed as creatinine ratios for the on-pump group increased significantly from 1.92+/-1.36, 6.06+/-3.62 and 0.21+/-0.07 before surgery to 11.88+/-5.77, 13.11+/-6.61 and 0.57+/-0.31 mmol/mol creatinine, respectively at arrival to the intensive care unit (ICU). During the next time-points, the purines and malondialdehyde decreased to 9.21+/-7.46, 7.55+/-3.95 and 0.32+/-0.13 mmol/mol creatinine, respectively after a 20 h stay at the ICU. For the off-pump CABG group, the mean ratios also increased significantly from 1.71+/-1.38, 2.01+/-0.96 and 0.16+/-0.10 before surgery to 4.73+/-3.19, 5.15+/-3.74 and 0.23+/-0.17 mmol/mol creatinine, respectively at arrival to the ICU. During the next time-points, the ratios of xanthine and malondialdehyde decreased to 3.80+/-2.92 and 0.24+/-0.13 mmol/mol creatinine, respectively. The ratio for hypoxanthine reached the highest ratio (6.97+/-5.67 mmol/mol creatinine) after a 9 h stay at the ICU, after which the ratio decreased to 5.98+/-5.56 mmol/mol creatinine after a 20 h stay at the ICU. However, all ratios from the on- and off-pump CABG patients still remained elevated compared with preoperative ratios. In addition, all ratios for the on-pump CABG group were elevated significantly at all time-points for xanthine, at time-points T2 and T4 for hypoxanthine and at time-point T2 for malondialdehyde as compared with the off-pump CABG group.


CONCLUSIONS
Only mild signs of oxidative stress and no renal dysfunction were found during and after off-pump CABG compared with on-pump CABG.
Gerritsen
W B
WB
Department of Clinical Chemistry, Sint Antonius Hospital, Nieuwegein, The Netherlands. w.gerritsen@kcl-azn.demon.nl
van Boven
W J
WJ
Driessen
A H
AH
Haas
F J
FJ
Aarts
L P
LP
D000368:Aged; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass / Q000379:methods*; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D019271:Hypoxanthine / Q000652:urine; D007668:Kidney / Q000502:physiology*; D007674:Kidney Diseases / Q000209:etiology; D008297:Male; D008315:Malondialdehyde / Q000652:urine; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D015427:Reperfusion Injury; D014527:Uric Acid / Q000652:urine; D019820:Xanthine / Q000652:urine
D019820:Xanthine; D014527:Uric Acid; D019271:Hypoxanthine; D008315:Malondialdehyde; D003404:Creatinine