Ischemic postconditioning diminishes intramyocardial hemorrhage in acute reperfused myocardial infarction in rats, evaluated by CMR at 7T

Abstract

Methods Twenty Sprague-Dawley rats (female, 250-300g) were divided into two groups: control group and IPOC group. The AMI model was built by ligating the left anterior descending coronary artery. All rats were subjected to 60 min ischemia, after that control group received direct reperfusion and IPOC group received 1 min of postconditioning (3 cycles of 10s reperfusion and 10s reocclusion) before permanent reperfusion. 48 hours later, all the rats were underwent cardiac magnetic resonance imaging (CMR) at 7.0T (Bruker BioSpect70/30, Germany). Cine (TR/TE=5.2ms/2.0ms, FA=10°, MTX=192×192, FOV=50×50mm, slice thickness=1.5mm), Late gadolinium enhancement (TR/ TE=5.2ms/1.8ms, FA=25°, MTX=256×256, FOV= 50×50mm, slice thickness=1.5mm) and simplified T2mapping (TR/TE=1500ms/10,20,30ms, MTX=192×192, FOV=50×50mm, slice thickness=1.5mm) were performed to acquire cardiac function indexes(EDV, ESV and EF), infarct size (LV%) and the area at risk (edematous area, LV%) respectively. All rats were sacrificed after CMR and the hearts were excised for hematoxylineosin staining. The results were expressed as mean ± SD and independent sample T-test was performed to determine difference between groups. Results Sixteen rats left (Control=9; IPOC=7) for three rats were died during operation and one was excluded for image artifacts. Intramyocardial hemorrhage size was significantly larger in control group compared with IPOC group(9.3±2.6% vs. 2.4±0.3%, P = 0.00).There was no significant difference was observed in infarct size (46.7±13.1% vs. 37.7±12.1%, P =NS), area at risk (65 ±11.8% vs. 51.4±13.2%, P = NS) and EF(57.7±12.4% vs. 57.6±13.5%, P = NS). Figure 1.