Anesthetic preconditioning combined with postconditioning offers no additional benefit over preconditioning or postconditioning alone

BACKGROUND: Recent investigations demonstrate that anesthetic preconditioning and postconditioning reduce myocardial infarct size to a degree comparable to that achieved with ischemic preconditioning. We hypothesized that the combination of sevoflurane preconditioning and postconditioning would result in greater preservation of myocardium. METHODS: Langendorff perfused rat hearts were divided into four groups: control, preconditioning, postconditioning, and preconditioning plus postconditioning. During reperfusion, left ventricular function (left ventricular developed pressure, left ventricular end diastolic pressure, and dp/dt) were measured. At the end of reperfusion, the infarct sizes were measured with 2,3,5 triphenyltetrazolium chloride staining. Nuclear magnetic resonance was used to measure intracellular pH, Na+, and Ca2+. RESULTS: Left ventricular developed pressure, left ventricular end diastolic pressure, left ventricular dp/dt(max) and dp/dt(min) were significantly improved in the treatment groups when compared with those in the controls. Myocardial infarct size (24% +/- 7%, 16% +/- 8%, and 22% +/- 7% in preconditioning, postconditioning, and pre-plus postconditioning groups versus 44% +/- 8% in the control group, P < 0.05) and intracellular Na+ and Ca2+ were significantly decreased in all experimental groups at the end of reperfusion when compared with those in control. However, there were no differences between these variables in each treatment group. CONCLUSION: Sevoflurane postconditioning is as effective as preconditioning in protecting myocardial function after global ischemia. The combination of sevoflurane preconditioning and postconditioning offered no additional benefit over either intervention alone.