[Beneficial effects of ischemic preconditioning on myocardial no-reflow in a mini-swine model of acute myocardial infarction and reperfusion].

OBJECTIVE

To evaluate the effects of ischemic preconditioning (IPC) on myocardial no-reflow in a mini-swine model of acute myocardial infarction (AMI) and reperfusion.

METHODS

Twenty-four mini-swines were randomized into 3 study groups: 8 in control, 8 in IPC and 8 in sham-operated. Animals in the former two groups were subjected to 3 hours of coronary occlusion followed by 1 hour of reperfusion. Data on hemodynamics and coronary blood flow volume (CBV) were collected, and the area of no-reflow (ANR) was evaluated with both myocardial contrast echocardiography (MCE) in vivo and pathological means. Necrosis area (NA) was measured with triphenyltetrazolium chloride (TTC) staining.

RESULTS

In control group, left ventricular systolic pressure (LVSP), the maximum change rate of left ventricular pressure rise and fall (+/-dp/dtmax) and cardiac output (CO) significantly declined (P < 0.05, P < 0.01), while left ventricular end-diastolic pressure (LVEDP) significantly increased at the end of 3 hours of left anterior descending coronary artery occlusion (both P < 0.01), with +/-dp/dtmax further significantly declined (both P <0.05) at 1 hour of reperfusion. In IPC group, LVSP, +/-dp/dtmax, CO and LVEDP significantly recovered at 1 hour of reperfusion, compared with those in control group. In IPC group, the coronary ligation area was similar on both MCE in vivo and pathological evaluation (P > 0.05), and ANR was both also similarly as high as (16.4 +/- 2.24) % and (17.5 +/- 2.87) %, respectively, with final necrosis area (NA) reaching (78.4 +/- 3.62) %. In IPC group, ANR and final NA were significantly lower than those in control group (P < 0.05, P < 0.01). In the control group, coronary blood flow volumn immediately after release of 3 hours occlusion and at 1 hour of reperfusion were significantly lower than the baseline (both P < 0.01). In IPC group, coronary blood flow volumn were significantly higher than those in the control group (both P < 0.01).

CONCLUSION

IPC is effective to prevent myocardial no-reflow, improve left ventricular function and decrease infarct area.