A Clinical Study On Mycocardial Protection Effect Of Sevoflurane Post-conditioning On Patients Undergoing Off-pump Coronary Artery Bypass Grafting

Objective:To determine mycocardial protection effect of sevoflurane postconditioning in off-pump coronary artery bypass grafting surgery. And study the mechanism of mycocardial protection of sevoflurane postconditioning.Methods:36patients undergoing OPCAB were randomly divided into three groups:control group (Cont group), sevoflurane preconditioning group(SPC group) and sevoflurane postconditioning group(SPO group). All patients were administrated by intravenous anesthetic drug, both for induction and maintenance. No special interventions were used in control group(Cont group). However, In SPC group,12patients inhaled sevoflurane at1.5MAC for5minutes first, with an interruption for10minutes, then continued for5minutes,30minutes before the anastomotic between mammary artery and anterior descending artery. In SPO group,12patients inhaled sevoflurane at1.5MAC for2minutes before the anastomosis of last one coronary artery, then continued for8minutes. We focus on four time points including T1(accomplishment of induction), T2(1hour after the coronary revascularization), T3(6hour after the coronary revascularization), T4(24hour after the coronary revascularization). Blood samples were drawn from the internal jugular vein for the measurement of the plasma concentrations of TNT-hs(highly sensitive cardiac troponin T),CK-MB(creatine phosphokinase isoenzyme), NT-proBNP(N-Terminal fragment of the prohormone Brain-Type Natri-uretic Peptide), TNF-a(tumornecrosis factor-a), MDA (malon diald ehyde). We also recorded blood pressure and heart rate at the following times:induction of anesthesia(t0),after induction of anesthesia(t1), sternotomy(t2),taking the first root of coronary artery(t3), accomplish-ment of coronary revascularization (t4),1hour after the coronary revascularization(t5),6hour after the coronary revascularization(t6),24hour after the coronary revascularization(t7).Results:All the patients completed the trials without significant adverse effects. The age, gender, ejection fraction, operative time,among three groups were statistically comparable (p>0.05). Stay time in postoperative ICU and hospital were less the Cont group(p<0.05). Compared with the pre-operative baseline, all patients’plasma concentrations of TNT-hs, CK-MB, NT-proBNP, TNF-a and MDA were significantly increased at1h,6h,24h after the coronary revascularization (p<0.05). TNT-hs in Cont group showed a persistnt increase, while in other two groups(including SPC group and SPO group),TNT-hs reached the peak concentrations at6hours after the coronary revascularizations, which were same with CK-MB, TNF-a and MDA in all groups; NT-proBNP reached the peak at coronary revascularization after24h. Compared with the Cont group, TNT-hs, CK-MB, TNF-a and MDA in SPC group and SPO group were significantly lower at6h,24h after the coronary revascularization(p<0.05); NT-proBNP was significantly lower only at24h after the coronary revascularization(p<0.05). There were no statistical differences of all the biochemical indicators between the SPO group and the SPC group except for the concentrations of MDA, in which MDA were higher in SPC group than in SPO group(p<0.05).Conclusions:1. At least, we proved that sevoflurane postconditioning in OPCAB have identified myocardial protection, which was comparable with sevoflurane preconditioning.2. Our study revealed that because sevoflurane preconditioning could inhibit the release of oxygen free radicals, inflammatory cytokines and myocardial enzymes, and it could significantly improve the myocardial function after the surgery, so it may be clinically useful for attenuating the ischemia and reperfusion injury.