ABSTRACT
Objective: To analyze the characteristics of multislice spiral computed tomography (CT) for acute myocardial infarction. Methods: The anterior descending coronary arteries of 6 pigs were ligated at the 1/3 distal end to establish acute myocardial infarction model without reperfusion. Dual multislice spiral CT scanning was performed in all animals and the CT characteristics were analyzed. Results: Acute myocardial infarction model was successfully established in all 6 animals. Myocardial perfusion deficits were detected during early phase scanning; the area of deficits were significantly decreased during late phase scanning (13.52 ± 5.22% vs 9.07 ± 3.47% P = 0.004), with a mean decrease of 32.14%. CT value of different myocardial varied at different scanning times: the values of LV cavity decreased from (586 ± 111) HU to (294±53) HU (P = 0.001), that of the normal myocardial area decreased from (247±54) HU to (132±25) HU (P = 0.001); the values of the perfusion deficit regions were not significantly changed ([42 ± 14] HU vs [29 ± 23] HU, P = 0.289). During late phase scanning, CT value around residual perfusion deficit was higher than that of normal myocardium ([156±21] HU vs [132±25] HU, P = 0.004). Conclusion: The dual-phase MSCT characteristics of AMI include early perfusion deficits, late enhancement and residual perfusion deficits. Early phase scanning may overestimate the infarction area.
ABSTRACT
Objective To investigate the role of apelin-13, a vasoactive peptide, in rat myocardial ischemia-reperfusion injury in vivo and explore its signal transduction pathway. Methods Rats were randomly divided into control group (n=10) and Apelin-13 group (n=15), and in vivo models of rat myocardial ischemia-reperfusion injury were established. Normal saline (control group) or Apelin-13 (Apelin-13 group) was administered intravenously 5 min before reperfusion. TTC and Evan's blue staining were used to determine the infarction size (IS) and area at risk (AAR), apoptotic cells were quantified by TUNEL method, and the expression of ERK1/2 was determined by Western blotting. Results IS/AAR and apoptosis index of Apelin-13 group were significantly lower than those in control group [(38.33±12.95) % vs (52.61±11.00)% and (0.21±0.02) vs (0.31±0.05)](P <0.05). The expression of p-ERK1/2 in Apelin-13 group was significantly increased than that in control group [(1.15±0.16) vs (0.63±0.07)](P < 0.05). Conclusion Apelin-13 may protect rat hearts from in vivo ischemia-reperfusion injury, reduce infarction size and attenuate myocardial apoptosis, which may be mediated by the activation of ERK1/2 MAPK signal transduction pathway.
ABSTRACT
Objective To explore the value of dual-phase contrast-enhancement multislice computed tomography (MSCT) in the assessment of acute myocardial infarction volume and perfusion in porcine models. Methods The distal left anterior descending coronary arteries of 5 pigs were balloon-occluded for 90 min and followed by reperfusion. MSCT was performed 1 min (early phase) and 5 min (delayed phase) after administration bolus of 100 mL of iodinated contrast material 30 min after reperfusion. On the same day, hearts were excised, sectioned in 8 mm short-axis slices, and stained with TTC. Infarction volume was defined as the sum of the hyper-enhanced area and surrounding hypo-enhanced area in all slices on delay enhanced phase of MSCT and the TTC-negative area on TTC staining slices. Infarction volume was expressed as percentage of total slice volume. Results Acute infarction detected by MSCT was characterized by early myocardial perfasion defects in the early phase of the contrast bolus (early defects) with surrounding residual defects and late enhancement observed in the late phase. Mean CT attenuation value of early defects was significantly different from CT attenuation value of remote myocardium [(213±55)HU vs (304±30)HU](P < 0.05), CT attenuation values of residual defects and late enhancement were also significantly different from those of remote myocardium [(360±75) HU vs (90±37) HU and (152±23) HU vs (190±37) HU, repectively](P < 0.01, P < 0.05). The mean infarction volume was (8.9± 1.0)% on MSCT and (9.2±1.4)% on TTC pathology images. The infarction volume assessed by MSCT compared well with TTC staining slices. Conclusion Acute reperfused myocardial infarction zone has specific enhancement pattens different to remote normal zone on dual phase MDCT, which is in good agreement with in vivo Trc pathology in the assessment of acute reperfused myocardial infarction shortly offer reperfusion.