真性动脉瘤破裂出血后假性动脉瘤的形成及血流动力学研究

目的研究颈总动脉（CCA）瘤破裂后假性动脉瘤的形成过程与机理。方法运用创伤法及显微外科技术,制作20只犬真性动脉瘤（AN）破裂出血后形成假性动脉瘤（真性合并假性动脉瘤,T＋F）模型,术后1、2、3、4、8周行彩色多普勒超声、磁共振成像（MRI）、磁共振血管成像（MRA）、数字减影血管成像（DSA）检查,光镜及电镜观察真性和假性动脉瘤的病理改变,计算流体动力学（CFD）模拟分析真性和假性动脉瘤内的血流速度、压力和切应力的分布情况。结果成功建立11只鼠T＋F模型,3只颈总动脉闭塞,2只真性AN闭塞,4只形成了真性AN而未形成假性AN。假性动脉瘤内的血流速度很慢,真性动脉瘤瘤口远端底边的切应力最高,而真性与假性动脉瘤交界的部位切应力不高。结论验证了T＋F形成的病理生理过程,提示假性动脉瘤的形成和生长可能与其内的压力有关。由于假性动脉瘤的形成,T＋F在血流动力学的影响下更容易破裂出血,应当积极地行确定性的外科治疗。

Formation and hemodynamics of pseudoaneurysm after rupture and bleeding of aneurysm: an experiment with dogs

Objective To study the process and mechanism of the formation of pseudoaneurysm after the rupture of aneurysm. Methods A model of aneurysm (AN) of the left common carotid artery (CCA) was made in 20 dogs. One to 2 weeks after the formation of AN, a localized hematoma connected with the AN was formed as a model of pseudoaneurysm after the rupture of true aneurysm (false aneurysm caused by the ruptured true aneurysm, T+F) was established. The models were examined by using color Doppler, magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and digital subtraction angiographies (DSA) 1, 2, 3, 4, and 8 weeks after the operation in all the animals. By the end of experiment the models of AN were taken out to undergo pathological examination by light and electron microscopy. The blood flow velocity, pressure on the walls and shear stress in the true and false aneurysm were analyzed by simulation of computational fluid dynamics (CFD) on these animal models. Results Experimental models of T+F were successfully created in the 11 dogs. CCA was successfully occluded in 3 dogs, true aneurysm was occluded in 2, and true aneurysms without pseudoaneurysm were produced in 4. The blood flow in the pseudoaneurysm was very slow. The pressure and shear stress were very high in the ends distal to the aneurysms and not high around the boundary between the true and false aneurysms. Conclusion The formation and growth of pseudoaneurysm are probably correlated with the pressure within the vessels. T+F should be positively and definitely treated by surgery to prevent them from rupture and bleeding.