Evaluation of perioperative myocardial tissue damage in ischemically preconditioned human heart during aorto coronary...

Preconditioning myocardium with short periods of ischaemic stress interspersed with reperfusion increases its resistance to infarction. Ischaemic preconditioning protection occurred in human beings during unstable angina preceding myocardial infarction, during percutaneous transluminal coronary angioplasty and during aorto coronary bypass surgery. The purpose of this study was to test (utilised cardiac troponin T measurement) whether ischaemic preconditioning was able to protect myocardial tissue during the perioperative period and how long that protection lasted.

Patients were recruited to the preconditioned group (n=29), received 4-min of aortic cross-clamping and 6 min reperfusion prior to CABG performed with intermittent ischaemic arrest and the control group (n=27) received only an ischaemic insult of operating procedure. TnT measurements were determined from blood samples taken before surgery (A), 1 hour after onset of CPB (B), 4 hours (C), 8 hours (D), 12 hours (E), 24 hours (F), 48 hours (G) and 72 hours after CPB (H).

Results were expressed as the median, range and standard deviation (SD) of TnT concentration (microg/l). Ischaemic preconditioning decreased TnT concentration with statistical significance 1 hour after onset of CPB (preconditioned B: median 0.12+/-0.25 vs control B: median 0.32+/-0.43, p=0.03). There were notable differences in TnT concentration in C, D, E, F, G, H blood samples between the control and the preconditioned group but with p value of no statistical significance.

These data illustrate that ischaemic preconditioning limits myocardial damage during operative procedure and it may probably afford protection during a postoperative period.