Biophysical insights into the relationship between plasma viscosity and atherogenic risk factors among patients who underwent CABG surgery

Plasma viscosity (PV) is an important determinant of blood flow and hemorheological behavior. Plasma plays a crucial role behaving as an interface between blood and vessel wall. Disturbed blood flow in atherosclerotic arteries, together with elevated plasma fibrinogen and endothelial dysfunction, may trigger mechanical stress on endothelial cells, from which nitric oxide (NO) is secreted. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase enzyme, is an increased marker for atherosclerosis. The present study was designed to investigate the relationship between PV and atherogenic risk factors in severe atherosclerotic patients underwent coronary artery bypass grafting surgery (CABG). Twenty-three male patients with severe atherosclerosis who underwent CABG were divided into two groups according to serum total cholesterol levels (Total-C) (Group 1(n:12): Total-C<200 mg/dL; Group 2(n:11): Total-C>200 mg/dL). PV, plasma fibrinogen, plasma NO and plasma ADMA were measured before operation (PreOp), on 1st day after operation (P1) and on 7th day after operation (P7). Group 1 had higher P1 and P7 plasma fibrinogen levels than PreOp (p<0.001) and Group 2 had higher P7 plasma fibrinogen levels than PreOp (p<0.05). PreOp PV was higher in Group 2 compared with Group 1 (p<0.05), whereas P7 PV levels decreased significantly after CABG operation in Group 2 (p<0.05). P7 PV levels were significantly higher than PV levels of PreOp and P1 in Group 1 (p<0.05). P1 PV levels of Group 2 decreased statistically significantly compared with PreOp levels (p<0.01). There was no statistically significant difference by means of plasma NO and ADMA levels among study groups. Group 2 had a less favorable serum lipid profile than Group 1. In conclusion, an unfavorable lipid profile and a higher atherogenic index before surgery, together with elevated PV levels, may reflect greater atherosclerotic burden in CABG patients. PV values decreased due to hydration and plasma fibrinogen increased just after surgery in both study groups. Higher fibrinogen levels despite hydration might be a result of high surgical stress, as an acute phase reactant. These findings suggest that the mechanical change of PV in early period after CABG might be more effective than plasma NO and ADMA.