| Objective: Because of myocardial infarction or severe angina, mostly patients with coronary heart diseases have varying degrees of cardiac dysfunction. For surgical treatment, it is important to accurately assess the perioperative cardiac function of patients for choose the opportunity of surgery, therapy and prognosis. The common methods to assess of cardiac functions in clinic are from New York Heart Association Grade (NYHA) and clinical symptoms, but they are subjective characteristics. Recent studies show serum BNP concentrations increase obviously when cardiomyocytes are stimulated by increment of ventricular loads and high wall tension. It shows significant relationship between BNP and cardiac function. BNP is now mainly confined to the evaluation of cardiac function in chronic heart failure. But the perioperative changes BNP in patients with coronary artery bypass grafting and related with heart function were less reported. The objective of the study is to explore the perioperative changes of serum BNP in patients undergoing coronary artery bypass grafting, evaluate the correlation between BNP and cardiac function, and provide an objective, quantitative indicator to decide therapy and predict prognosis.Methods: Patients were divided into 3 groups: control group, CCABG group, OPCABG group. Control group: The BNP concentrations of 20 healthy people as a basic control concentrations. The number of patients in CCABG group and OPCABG group are 18, 21 respectively. Blood samples were collected from peripheral vein at 1 day before operation (T1), 7 hours(T2), 1day(T3), 3 days(T4), 5 days(T5) and 7 days(T6) after operation. BNP concentrations were determined by ELISA. The NYHA grades were assessed and the LVEF was measured by echocardiogram before operation. Meanwhile observe the TnI concentrations, the application of cardiovascular drugs at 24 hours,the support time of ventilator, ICU time, hospitalizetion and postoperative complications after operation.Results: 1.There was no difference in perioperative BNP and LVEF between female and male patients (P>0.05). 2.The mean BNP concentrations of coronary heart diseases patients was marked higher than that of the healthy control populations(T1:117.75±82.33pg·ml-1 vs. 23.23±11.55 pg·ml-1,P<0.0001). There was a positive correlation between NYHA and BNP (r=0.719, P<0.01), worse in cardiac function, higher in BNP concentrations. There was a negative correlation between LVEF and BNP (r=-0.829, P<0.01), lower in LVEF, higher in BNP concentrations. Among NYHA grades, BNP concentrations have significant difference (P<0.05), also LVEF have significant difference (P<0.05) except between NYHA II and III grade. 3. The postoperative BNP concentrations of all patients were T2:242.34±111.35pg·ml-1, T3:294.04±134.39pg·ml-1, T4:256.33±122.71pg·ml-1,T5:200.30±117.52pg·ml-1,T6:153.87±99.84pg·ml-1, respectively. The preoperative BNP level was the baseline, it elevated sharply at 7 hours after operation and reached a peak at 1 day after operation, then the BNP decreased at 3 day after operation, 4 days later it was still higher than the concentrations before operation, but there was no difference in statistics(P>0.05).4. The postoperative BNP of CCABG group and OPCABG group were T2:273.66±116.32pg·ml-1 vs. 215.49±102.07 pg·ml-1,P=0.105;T3:345.58±131.43pg·ml-1 vs. 249.86±123.27 pg·ml-1,P=0.025;T4:304.36±124.94pg·ml-1 vs. 215.16±107.17 pg·ml-1,P=0.022;T5:239.86±126.43pg·ml-1 vs. 166.39±100.19 pg·ml-1,P=0.050;T6:179.03±108.73pg·ml-1 vs. 132.27±88.49 pg·ml-1,P=0.147. CCABG group's BNP concentrations was higher than OPCABG group's after operation, and there were significant difference at the 1 day and 3 day after operation (P<0.05). There were no significant difference in the support time of ventilator, the application of cardiovascular drugs, arrhythmia, respiratory dysfunction, stroke and mortality, but all of those had lower incidence in OPCABG group. The TnI concentrations at 24 hours after operation increased lower in OPCABG group(11.93±9.60ng·ml-1 vs. 24.08±16.74ng·ml-1, P=0.007). 5. Compared to non-AMI patients, AMI patients'preoperative NYHA grades and the perioperative BNP were higher and LVEF value were lower, there were significant difference between two groups (P<0.05), but TnI concentrations at postoperative 24 hours had no significant difference (P>0.05). 6. Compared with low concentration group bounded by BNP 100pg·ml-1 before surgery, the preoperative LVEF of high concentration group were lower (P<0.05). Postoperative TnI concentrations, the application of cardiovascular drugs, the support time of ventilator and the incidence of postoperative complications were higher significantly (P<0.05).Conclusions: 1.The serum BNP concentrations can reflect the perioperative cardiac function of patients undergoing coronary artery bypass grafting.,poorer in cardiac function,higher in BNP concentrations. 2. BNP is more accurate to quantify the cardiac function than LVEF. 3. Compared with CPB, off-pump CPB is more profitable to the recovery of cardiac function in patients undergoing coronary artery bypass grafting. 4. BNP is an objective, quantitative indicator for deciding therapy and predicting prognosis in coronary artery bypass grafting. The patients with preoperative BNP≥100pg·ml-1 have poor prognosis.
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