Ma Jian-Ying, Qian Ju-Ying, Jin Hang, Chen Zhang-Wei, Chang Shu-Fu, Yang Shan, Sun Ai-Jun, Zeng Meng-Su, Zou Yun-Zeng, Ge Jun-Bo
Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Chin Med J (Engl). 2009 Mar 20;122(6):687-91.
Detection of coronary microembolization is of clinical importance for patient management and prediction of long-term outcome. However, there are few studies of the changes of magnetic resonance imaging after coronary microembolization. This study was designed to investigate the imaging of the left ventricle using delayed contrast enhanced magnetic resonance imaging as well as the left ventricular ejection fraction after coronary microembolization in animal models.
Eight miniswine, of either sex (body weight 21-25 kg), were used to make the coronary microembolization model. After coronary angiography, a 2.8F infusion catheter was placed in the left anterior descending artery with the tip located between the second and third diagonal branches. Microspheres with the diameter of 42 microm and mean dosage of 1.2 x 10(5) were selectively infused into the left anterior descending artery. First pass and stressed first pass perfusion scan were performed after cine images were acquired. Then a second bolus of 0.15 mmol/kg gadolinium DTPA was given at a rate of 2 ml/s. Ten minutes later, delayed contrast enhanced magnetic resonance images of the left ventricular wall were evaluated. Serum changes of tumor necrosis factor alpha (TNF-alpha) were evaluated by enzyme-linked immunosorbent assay (ELISA).
Hypoenhancement was not observed at first pass perfusion at the anterior wall of the left ventricle. Hyperenhancements of the anterior-septal and anterior wall of the left ventricle was in evidence on delayed enhancement images 6 hours after microembolization and disappeared one week later. The characteristic change of coronary microembolization on delayed contrast enhanced magnetic imaging was non-enhanced regions within the hyperenhancement zone. Left ventricular ejection fraction measured by magnetic resonance imaging decreased significantly from 0.451 +/- 0.063 at baseline to 0.362 +/- 0.070 at the sixth hour (P < 0.01), and recovered to 0.431 +/- 0.053 one week later (P < 0.01 vs 6th hour). Compared with baseline values, the left ventricular end systolic volume enlarged significantly at 6th hour and at one week after microembolization (P < 0.05 and P < 0.01 respectively). Serum TNF-alpha increased significantly at 6th hour (22.62 +/- 6.96) pg/ml compared with baseline (16.83 +/- 3.45) pg/ml (P < 0.05) and it further increased to (27.44 +/- 3.97) pg/ml at one week after coronary microembolization and was significantly higher than that at baseline (P < 0.01).
On delayed contrast enhanced magnetic resonance imaging, hyperenhancement of the anterior-septal and anterior wall of the left ventricle show at 6th hour but not at one week after coronary microembolization. This might represent the characteristic imaging after coronary microembolization. The left ventricular ejection fraction decreased at 6th hour and recovered one week later after coronary microembolization. Although impairment of left ventricular function could be recovered at 1 week after coronary microembolization, the left ventricular remodeling process still continued in concert with continuously elevation of serum TNF-alpha.
检测冠状动脉微栓塞对于患者管理和长期预后的预测具有临床重要性。然而，关于冠状动脉微栓塞后磁共振成像变化的研究较少。本研究旨在利用延迟对比增强磁共振成像研究动物模型冠状动脉微栓塞后左心室的成像以及左心室射血分数。
选用8只体重21 - 25 kg的雌雄不限的小型猪制作冠状动脉微栓塞模型。冠状动脉造影后，将一根2.8F的输注导管置于左前降支动脉，导管尖端位于第二和第三对角支之间。将直径为42微米、平均剂量为1.2×10⁵的微球选择性地注入左前降支动脉。在采集电影图像后进行首次通过和负荷首次通过灌注扫描。然后以2 ml/s的速率给予第二剂0.15 mmol/kg的钆喷替酸葡甲胺。10分钟后，评估左心室壁的延迟对比增强磁共振图像。通过酶联免疫吸附测定（ELISA）评估肿瘤坏死因子α（TNF-α）的血清变化。
左心室前壁首次通过灌注时未观察到强化减低。微栓塞后6小时延迟增强图像上可见左心室前间隔和前壁强化增加，1周后消失。延迟对比增强磁共振成像上冠状动脉微栓塞的特征性变化是强化增加区内的无强化区域。磁共振成像测量的左心室射血分数从基线时的0.451±0.063显著下降至第6小时的0.362±0.070（P < 0.01），1周后恢复至0.431±0.053（与第6小时相比P < 0.01）。与基线值相比，微栓塞后第6小时和1周时左心室收缩末期容积显著增大（分别为P < 0.05和P < 0.01）。血清TNF-α在第6小时显著升高，从基线时的（１６.８３±３.４５）pg/ml升至（２２.６２±６.９６）pg/ml（P < 0.05），冠状动脉微栓塞1周后进一步升至（２７.４４±３.９７）pg/ml，显著高于基线水平（P < 0.01）。
在延迟对比增强磁共振成像上，冠状动脉微栓塞后6小时可见左心室前间隔和前壁强化增加，1周后则无。这可能代表冠状动脉微栓塞后的特征性成像。冠状动脉微栓塞后第6小时左心室射血分数下降，1周后恢复。尽管冠状动脉微栓塞1周后左心室功能损害可恢复，但左心室重构过程仍与血清TNF-α持续升高同步进行。
