Myocardial metabolism on off-pump surgery; a randomized study of 50 cases

To study the inflammatory reaction and myocardial metabolism in off-pump and on-pump coronary artery bypass patients.

Fifty coronary artery bypass patients were randomized to off-pump or on-pump operations. Myocardial biopsies were taken to determine myocardial metabolism and inflammation (glutathione (GSH), superoxide dismutase (SOD) and myeloperoxidase (MP)) and plasma samples for indicators of oxidative stress (conjugated dienes (s-BDC), oxidative products of proteins (s-ox-Prot) and low-density lipoprotein (LDL)-total peroxyl radical trapping antioxidant potential (s-TRAP)).

s-ox-Prot 10 min was 2.11 +/- 0.75 vs 2.69 +/- 0.60 (p = 0.014), s-TRAP 5 min was 861 +/- 180 vs 969 +/- 192 (p = 0.032) and s-TRAP 10 min 857 +/- 176 vs 985 +/- 166 (p = 0.011), GSH 10 min 0.55 +/- 0.19 vs 0.72 +/- 1.16 (p = 0.007) (off-pump vs on-pump). The monobasic (MB) fraction of the creatinine kinase 24 h after the operation was significantly lower in the off-pump group, 20.5 +/- 24.2 vs 61.8 +/- 84.6 (p = 0.023).

GSH levels from the biopsies were increased in the perfusion group early in the reperfusion time showing that myocardial tissue was well protected and recovered more rapidly after cross-clamping than after the occlusion of the coronary arteries. However, release of creatinine kinase was lower in the off-pump group showing that cardiopulmonary bypass has more deleterious effects later after the operation.