Objective      To examine the changes of the concentration of plasma circulating cell-free DNA (cf-DNA) during cardiopulmonary bypass (CPB) open-heart surgery

and the changes of hepatic function

renal function and myocardial enzymes before and after operation

and to explore the significance.       Methods      Twenty-five patients admitted in our hospital from September 2012 to December 2012 wer

e enrolled. Thirteen patients with coronary artery disease underwent coronary artery bypass graft (CABG) were enrolled as a CABG group and 12 patients with rheumatic heart disease underwent double valve replacement (DVR) were enrolled as a DVR group. Venous blood was collected for the determination of hepatic function

renal function and myocardial enzymes

and plasma cf-DNA was detected by fluorescent semi-quantitative PCR.       Results      The concentration of plasma cf-DNA was elevated significantly during CPB in both groups

it peaked at the end of CPB

and decreased along with time extending. However

the concentration of plasma cf-DNA at 48 h after operation was still higher than that before CPB. The decrease of plasma cf-DNA in the CABG group was significantly faster than that in the DVR group (

P

0.05). The changes of plasma cf-DNA before and after operation were significantly correlated with total bilirubin and urea nitrogen (

P

0.01).       Conclusion      Plasma cf-DNA can monitor the injury of patients during CPB

and may be a valuable marker for the diagnosis and prediction of CPB complications.