Inducible HSP70 levels in thoracic wound fluid indicate myocardial damage after open heart surgery

Heat shock proteins (HSP) act as chaperones and protect cellular homeostasis. They are induced by multiple forms of cell stress. Nothing is known about their rise in the drainage fluid after cardiac and thoracic operations.

Forty-five patients undergoing open heart surgery or major lung resections were studied. Levels of inducible HSP70 were measured daily in thoracic wound fluid and blood with ELISA tests in addition to multiple conventional blood and wound fluid parameters. Data were analyzed using analysis of covariance and Spearman's rank-correlation coefficient.

Inducible HSP70 was detectable in all thoracic fluid samples. Mean HSP70-level after open heart surgery was 64 ng/mL and 40 ng/mL in patients without extracorporeal circulation (P=0.015). Drainage HSP70 levels were correlated with white blood cell counts in wound fluid (P<0.0001) and blood CK-MB levels (P<0.0001). Correlation coefficients between white blood cells in blood and local HSP-levels were explicitly lower (P=0.0023). There was a steady decrease in HSP levels in drainage fluid from day 1 to day 4 (P<0.0001).

Inducible HSP70 is present in postoperative thoracic drainage fluid. Drainage levels are higher in patients after open heart surgery and are correlated with blood CK-MB levels, indicating cardiomyocyte damage. Our data further suggest that extracellular HSP70 is released also by white blood cells. Additional studies are needed to examine the role of extracellular HSP70 in wound healing processes and myocardial damage.