Oxidative stress in coronary artery bypass surgery

Objective

The aim of this prospective study was to assess the dynamics of oxidativestress during coronary artery bypass surgery with cardiopulmonarybypass.

Methods

Sixteen patients undergoing coronary artery bypass grafting were enrolled.Blood samples were collected from the systemic circulation during anesthesiainduction (radial artery - A1), the systemic venous return (B1 and B2) fourminutes after removal of the aortic cross-clamping, of the coronary sinus(CS1 and CS2) four minutes after removal of the aortic cross-clamping andthe systemic circulation four minutes after completion of cardiopulmonarybypass (radial artery - A2). The marker of oxidative stress,malondialdehyde, was measured using spectrophotometry.

Results

The mean values of malondialdehyde were (ng/dl): A1 (265.1), B1 (490.0), CS1(527.0), B2 (599.6), CS2 (685.0) and A2 (527.2). Comparisons between A1/B1,A1/CS1, A1/B2, A1/CS2, A1/A2 were significant, with ascending values(P<0.05). Comparisons between the measurements ofthe coronary sinus and venous reservoir after the two moments of reperfusion(B1/B2 and CS1/CS2) were higher when CS2 (P<0.05).Despite higher values ​​after the end of cardiopulmonary bypass (A2), whencompared to samples of anesthesia (A1), those show a downward trend whencompared to the samples of the second moment of reperfusion (CS2)(P<0.05).

Conclusion

The measurement of malondialdehyde shows that coronary artery bypass graftingwith cardiopulmonary bypass is accompanied by increase of free radicals andthis trend gradually decreases after its completion. Aortic clampingexacerbates oxidative stress but has sharper decline after reperfusion whencompared to systemic metabolism. The behavior of thiobarbituric acid speciesindicates that oxidative stress is an inevitable pathophysiologicalcomponent.