[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.