Adenosine Preconditioning In Off-Pump Coronary Artery Bypass Graft Surgery

Objective To investigate the effect of adenosine preconditioning during off-pump coronary artery bypass graft surgery (OPCAB).Method Patients undergoing elective off-pump CABG with normal ventricular function (ejection fraction≥40%), and with at least three vessel disease were selected for study. The 40 patients were allocated to two groups randomly (n=20 ADO, and n=20 control). ADO group received infusion of ADO when the surgery dissociation left internal mammary artery, through a catheter via internal jugular vein. The initial infusion rate was 50 ugkg^-1' min^-1, the rate of infusion was increased every minute by 50 ug·kg^-1·min^-1, until the dose 150 ug·kg^-1·min^-1, maintain this rate to 10min. The control group received 0.9% saline instead during the infusion period. 5min after the completion of adenosine or saline infusion protocol, revascularization began. Hemodynamic parameters were documented at following time points: To (10 minutes after anesthesia), T₁(30 minutes after revascularization), T₂, T₃, T₄ and T₅ (2 hours, 6 hours, 12 hours and 24 hours respectively afterwards). Blood samples were collected simultaneously for MB isoenzyme of creatine kinase (CK-MB), cardiac troponinâ… (cTnI) and NT-pro Brain Natriuretic Peptide (NT-proBNP) measurement. Right atrial myocardial were harvested before and 15 minutes after revascularization respectively, for analyzing the ultrastructure and TNF-αmRNA and ICAM-1mRNA expression. Resultsâ‘ Compared with the baseline, there were no significantdifferences in blood pressure postoperatively, but HR increased significantly (P＜0.01), pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP) and mean pulmonary artery pressure (MPAP) increased significantly (P＜0.01). Cardiac output (CO) and cardiac index (CI) increased markedly (P＜0.01). Systemic vascular resistance (SVR), systemic vascular resistance index (SVRI), stroke volume (SV) and stroke volume index (SVI) and left ventricular stroke work index (LVSWI) decreased significantly, while right ventricular stroke work index (RVSWI) was decreased transiently (ADO group at T1 and control group at T2, P＜0.01). Compared with the control group, CO and CI of ADO group increased markedly at T2 (P＜0.01).â‘¡Compared with the baseline, CK-MB of control group increased from T₁ to T₅ (P＜0.05), that of adenosine group increased only at T2 (P＜0.05), patients of ADO group released significantly less CK-MB at T5(P＜0.01). Compared with the baseline, cTnI increased significantly from T1 to T5 (P＜0.05) in both groups, patients of ADO group released less cTnI than control group, especially at T4 and T5 point (P＜0.05). NT-proBNP of both groups increased at T5 (P＜0.01), there were no differences between the two groups.â‘¢The myocardial ultrastructure of control group after revascularization was damaged more seriously than that of ADO group.â‘£The expression of TNF-αmRNA in ADO group decreased than the control group, but not significant(P=0.07). ICAM-lmRNA expression decreased significantly in ADO group (P=0.048). Conclusion The performance of OPCAB result in ischemia/reperfusion injury and heart function inhibition, especial left ventricular function. Adenosine preconditioning can reduce the release of CK-MB and cTnI, but can not improve cardiac function postoperatively. Adenosine preconditioning can reduce the expression of TNF- e and ICAM-1 mRNA.