Reinfusion of shed blood after coronary operation causes elevation of cardiac enzyme levels.

We studied the effect of reinfusing mediastinal and chest tube drainage (autotransfusion) after coronary artery bypass grafting on circulating levels of creatine kinase, lactate dehydrogenase, and serum glutamic-oxaloacetic transaminase in 20 patients. Reinfusion of 469 +/- 171 mL (mean +/- standard deviation) of drainage caused enzyme levels to rise to 372% (creatine kinase), 159% (serum glutamic-oxaloacetic transaminase), and 143% (lactate dehydrogenase) of their levels before autotransfusion. The MB fraction of the circulating creatine kinase was not elevated. Enzyme changes caused by autotransfusion can potentially mimic or mask the presence of perioperative myocardial infarction. Enzyme determinations after coronary artery bypass grafting must be carefully interpreted when reinfusion of shed blood is used as a blood salvage technique. Routine measurement of these enzymes after operation may not be warranted.