分次栓塞脑血管致犬脑循环自体重建的实验研究

Experimental study on the reconstruction of the cerebral circulation from successive canine cerebral embolism

目的建立犬脑循环储备下降动物模型,探讨分次栓塞脑血管分支对犬脑循环的影响以及脑血运自体重建的时间跨度。方法 18只成年杂种犬随机分为A、B、C、D 4组,同时或依次栓塞左、右侧椎动脉、左、右侧颈内动脉,A组为正常对照组(n=3),B组为每隔1 w依次栓塞组(n=5),C组为每隔2 w依次栓塞组(n=5),D组为同时栓组(n=5)。采用MRI灌注成像检测脑血流量(CBF),MRI或CT检测犬脑影像学改变,DSA观察脑血管再生及侧枝循环建立情况,整体行为分类法评定神经功能。结果分次栓塞与一次性栓塞比较,犬脑CBF下降程度明显降低;且C组CBF下降程度较B组轻。依次栓塞左、右侧椎动脉,B、C组颈总动脉与脑底动脉侧枝循环开放,颈内动脉扩张,未见新生血管形成;再依次栓塞左、右侧颈内动脉,B、C组均有新生血管形成,C组更为明显;8 w复查两组颅内血管均明显增粗、增多。影像学检查:D组见多发性梗死灶或(和)大面积脑梗死;B组见个别动物呈现基底节区梗死,C组未见明显梗死灶。神经功能评分:D组5分,所有动物均在术后8 h内死亡;B组1只犬残留2级神经功能缺损;C组均未发生神经功能障碍(1级)。结论分次栓塞犬脑血管可以促使犬脑血管侧枝循环形成、脑循环重建;分次栓塞间隔时间越长,犬脑脑血流量下降越缓慢;犬脑循环储备下降至失代偿期,至少需要2 w时间才能重建充分有效的侧枝循环,分次栓塞4根犬脑主要供血动脉,至少需要8 w才能完成脑循环重建及脑血流储备。

Objective To establish reduced cerebral circulation reserve canine model, explore the effect of succes- sive embolization of cerebral vascular on cerebral circulation, and observe time for self reconstruction of cerebral blood circu- lation. Methods 18 hybrid adult dogs were randomly divided into four groups including group A, group B, group C and group D. Left and right vertebral artery, and left and right internal carotid artery were simultaneously or successively emboli- zed. Group B （ n = 5 ） was successively embolized every one week, group C （ n = 5 ） every two week, group D （ n = 5 ） simul- taneously and group A （n = 3 ） as normal control. Change of CBF after embolization were detected by perfusion weighted MR imaging. Canine cerebral radiographic change were tested by MRI or CT. Cerebral vascular regeneration and collateral circulation reconstruction were observed by DSA. Neurological function was scored by whole behavior classification. Re- suits Canine CBF decreased more obviously in simultaneous embolization group than in successive embolization group, and group C superior to group B. Common carotid artery and collateral circulation of basal cerebral arteries opened in group B and group C after successive embolization of left and right vertebral artery, and dilated internal carotid artery was found with- out new vascular formation. When left and right internal carotid artery were further embolized, new vascular were formed in group B and group C, and group C more obviously. Intracranial cerebral vascular enlarged and increased in both group B and group C after 8W. MRI showed multiple or/and massive infarction in group D. CT showed basal ganglia infarct in some animals in group B. there was no infarction in group C. All the animals in group D died 8h postoperatively （ neurological function scoring：5）. Moderate neurological function deficit occurred in one dog in group B. There was no neurological function deficit in group C （ neurological function scoring： 1 ）. Conclusion Successive embolization of cerebral vascular can promote collateral circulation formation and cerebral circulation reconstruction. The longer embolization interval time, the slower CBF decrease. At least 2 weeks were necessary for reconstruction of efficient collateral circulation after cerebral circulation reserve decreased to decompensation phase. At least 8 weeks were necessary for reconstruction of cerebral circu- lation and CBF after successive embolization of cerebral vascular.