On-pump versus off-pump coronary artery bypass grafting: more heat-shock protein 70 is released after on-pump surgery.
OBJECTIVE
The use of cardiopulmonary bypass in coronary artery bypass grafting (CABG) may contribute to the postoperative inflammatory response. The molecular chaperone heat-shock protein (HSP) 70 may be induced by ischemia, and has been detected both in the myocardium and in the circulation after CABG. In vitro, extracellular HSP70 may activate both innate and adaptive immunity. Hypothesizing that use of cardiopulmonary bypass (CPB) leads to more circulating HSP70, we explored the release of it in 10 patients undergoing CABG with the use of CPB, and in 10 patients undergoing off-pump surgery CABG (OPCAB).


METHODS
Blood samples were taken preoperatively, twice peroperatively, 2 and 6 h postoperatively and the next day. Serum analyses were performed by means of immunoassays.


RESULTS
We detected a significant difference in postoperative circulating HSP70 between on-pump and off-pump patients (median peaks of 2849 and 756 pg/ml, respectively, P < 0.01 2 h postoperatively). Interleukin-6 and -8 increased in all patients, without significant differences between the groups. Serum interleukin-10 increased at the end of the operation in 7 of 10 patients operated with cardiopulmonary bypass (median 51.7 pg/ml), but in none of the off-pump patients. Furthermore, in the first group, interleukin-10 correlated with the HSP70 concentration at the end of the operation, r = 0.75, P < 0.05. Serum markers of myocardial damage were higher in conventional than off-pump patients on day 1 postoperatively: median cardiac Troponin T was 0.358 and 0.126 microg/l, respectively, P < 0.01. Correspondingly, median creatine kinase-MB was 23.6 and 7.8 microg/l in on-pump and off-pump patients, respectively, P < 0.001. Peak HSP70 correlated with both Troponin T and creatine kinase-MB measured on day 1.


CONCLUSIONS
Significantly more HSP70 was released into the circulation following conventional than following off-pump CABG. Circulating HSP70 may indicate cellular stress or damage. Furthermore, HSPs are suggested as immunoregulatory agents, and may be important in the host defence postoperatively.
Dybdahl
Brit
B
Faculty of Medicine, Institute of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway. brit.dybdahl@ulleval.no
Wahba
Alexander
A
Haaverstad
Rune
R
Kirkeby-Garstad
Idar
I
Kierulf
Peter
P
Espevik
Terje
T
Sundan
Anders
A
D000368:Aged; D015415:Biomarkers / Q000097:blood; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D001026:Coronary Artery Bypass / Q000379:methods*; D003402:Creatine Kinase / Q000097:blood; D052279:Creatine Kinase, MB Form; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000097:blood*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007378:Interleukins / Q000097:blood; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000097:blood / Q000209:etiology; D011184:Postoperative Period; D020107:Troponin T / Q000097:blood
D015415:Biomarkers; D018840:HSP70 Heat-Shock Proteins; D006454:Hemoglobins; D007378:Interleukins; D007527:Isoenzymes; D020107:Troponin T; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form