Myocardial injury in coronary artery bypass grafting: On-pump versus off-pump comparison by measuring heart-type fatty-acid-binding protein release.

This prospective study uses heart-type fatty-acid-binding protein (hFABP) and creatine kinase-MB (CK-MB) release to compare myocardial injury in on-pump versus off-pump coronary artery bypass grafting (CABG). Fifty patients were randomly assigned to on-pump or off-pump CABG. The hFABP and CK-MB concentrations were measured in serial venous blood samples drawn before heparinization in both groups and after aortic unclamping at 1, 2, 4, 8, 24, 48, and 72 hours in the on-pump group. In the off-pump group, samples were taken after the last distal anastomosis at the same time intervals as in the on-pump group. The total amount of hFABP and CK-MB released was significantly higher in the on-pump than in the off-pump group (hFABP = 100.43 +/- 77.63 vs 3.94 +/- 0.36 ng/mL, P < 0.0001; CK-MB = 33.33 +/- 3.81 vs 28.65 +/- 3.91 log units, P < 0.001). In all patients, hFABP levels peaked as early as 1 hour after declamping (on-pump group) or 2 hours after the last distal anastomosis (off-pump group), whereas CK-MB peaked only at 4 hours after declamping (on-pump group) or 24 hours after the last distal anastomosis (off-pump group). The lower release of hFABP and CK-MB in the off-pump CABG group indicates that on-pump CABG with cardioplegic arrest causes more myocardial damage than does off-pump CABG. Heart-type fatty-acid-binding protein is a more rapid marker of perioperative myocardial damage, peaks earlier than CK-MB, and may predict the requirement for intensive monitoring for postoperative myocardial infarction.

A comparative study of release of interleukin-6 and tumour necrosis factor during normothermic and hypothermic cardiopulmonary bypass.

The institution of cardiopulmonary bypass generates many pro-inflammatory cytokines and several clinical variables, including temperature, have been shown to influence cytokine release during and after cardiopulmonary bypass. The release of tumour necrosis factor and interleukin-6 are the best predictors of post-cardiopulmonary bypass related morbidity. Their release during normothermic and hypothermic cardiopulmonary bypass and the correlation with clinical parameters of organ injury was studied. This prospective study was carried out in 52 adult patients, scheduled for cardiac surgery, exposed to normothermic and 27 to hypothermic cardiopulmonary bypass. Samples for estimation of tumour necrosis factor and interleukin-6 were collected preoperatively, 1 hour and 24 hours post cardiopulmonary bypass and analysed by ELISA. Haemodynamic parameters and respiratory parameters were noted and lung injury scores calculated. Interleukin-6 levels were raised in both the groups at 1 hour and 24 hours post cardiopulmonary bypass and the response was higher in the normothermic group. Tumour necrosis factor response was, however, similar in both the groups, with a rise at 1 hour returning back to baseline by 24 hours post cardiopulmonary bypass. The normothermic group had a better respiratory index in the postoperative period, early extubation was possible, had better clinical haemodynamics, a shorter cardiopulmonary bypass time and had reduced requirement of defibrillation after the release of aortic cross clamp. We conclude that the release of interleukin-6 was thermo-dependent but did not correlate with the clinical signs of organ injury. Tumour necrosis factor levels were significantly raised after the cardiopulmonary bypass but the rise was not thermo-dependent.