Level of serum NT-proBNP at time points Time NT-proBNP (pg / ml) ± SD Median N0 491.2 ± 601.1 364.7 N1 972.5 ± 1608.05 838.5 N2 1915.1 ± 2513 1792.4 N3 4057.26 ± 4458.12 3766.2 N4 3981.78 ± 4549.03 3157.1 N5 3457.81 ± 4110.98 2845.3 p < 0.05 Comment: After surgery, the mean of NT-proBNP level increased slightly at N1 with 972.5 pg / ml, then increased fastly and peaked at N3 with 4057.26 pg / ml, and then tending decreased gradually at N5 with 3457.81 pg/ml.