• José Milei, Pedro Forcada, César G Fraga, Daniel R Grana, Gabriele Iannelli, Massimo Chiariello, Isabella Tritto, and Giuseppe Ambrosio.
• Instituto de Investigaciones Cardiológicas Alberto C. Taquini UBA-Conicet, Buenos Aires, Argentina.
• Cardiovasc. Res. 2007 Mar 1;73(4):710-9.

ObjectiveIn animal models, formation of oxidants during postischemic reperfusion may exert deleterious effects ("oxidative stress"). Cardioplegic arrest/reperfusion during cardiac surgery might similarly induce oxidative stress. However, the phenomenon has not been precisely characterized in patients, and therefore the role of antioxidant therapy at cardiac surgery is a matter of debate. Thus, we wanted to ascertain whether the relationship between oxidant formation and development of myocardial injury also translates to the situation of patients subjected to cardioplegic arrest.MethodsIn 24 patients undergoing coronary artery bypass, trans-cardiac blood samples and myocardial biopsies were taken before cardioplegic arrest and again following reperfusion.ResultsCardiac glutathione release (marker of oxidant production) was negligible at baseline (0.02+/-0.04 micromol/L), but it increased 15 min into reperfusion (1.10+/-0.40 micromol/L; p<0.05); concomitantly, myocardial concentration of the antioxidant ubiquinol decreased from 144.5+/-52.0 to 97.6+/-82.0 nmol/g (p<0.05). Although these changes document cardiac exposure to oxidants, they were not accompanied by evidence of injury. Neither coronary sinus blood nor cardiac biopsies showed increased lipid peroxide concentrations. Furthermore, electron microscopy showed no major ultrastructural alterations. Finally, full recovery of left ventricular systolic and diastolic function was observed.ConclusionsCareful investigation reveals that while oxidant production does occur during cardiac surgery in patients with chronic ischemic heart disease, cardiac oxidative stress may not progress through membrane damage and irreversible injury.

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