[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.

Study on intraluminal embolization with microcoils treating traumatic pseudoaneurysms in common carotid artery in rabbits.

OBJECTIVE: To evaluate the long-term effect of endovascular occlusion with microcoils on traumatic pseudoaneurysms (TPAs) in the common carotid artery in rabbits. METHODS: TPAs in the right common carotid artery were surgically made in 16 rabbits. At 3-4 weeks after operation, the survived 12 models were randomly divided into a control group (n=3) with no treatment and an experimental group (n=9), in which TPAs were intraluminally embolized with microcoils and corresponding therapy was given. Three months after embolization, the TPAs were examined with digital subtraction angiography and pathology. RESULTS: The 3 rabbits in the control group all died of rupture of TPA. Among the 9 TPAs occluded with microcoils, 4 were completely occluded, 4 were partially occluded, and 1 was excluded due to the microcoils migrating into the parent artery. Three months after embolization, the 4 TPAs which were completely occluded remained obliterated as determined by digital subtraction angiographic findings. The parent artery remained unobstructed and the structure of the TPAs were replaced by a mass of scar tissues. The 4 TPAs which were partially occluded remained unruptured and the microcoils were compressed. CONCLUSIONS: The lumen in TPA can be completely occluded by microcoils and the parent artery is unblocked. Partial occlusion of the lumen can also prevent the rupture of TPA.

Early diagnosis of cerebral infarction with near-infrared spectroscopy: an experimental study.

OBJECTIVE: To monitor the changes in the blood flow and blood-oxygen content in rat cerebral tissue with focal cerebral infarction using near-infrared spectroscopy (NIRS), so as to verify the value of NIRS in early diagnosis of cerebral infarction. METHODS: Focal cerebral infarction models were established in 16 rats by injecting silk threads into the internal carotid artery. The bilateral blood flow and blood-oxygen content were monitored with NIRS in the models and also in 16 normal rats receiving saline injection to serve as blank control group. RESULTS: Focal cerebral infarction in rats caused the decrement in blood-oxygen content and the increase in blood flow. No changes were observed in the control group after saline injection (P >0.05). CONCLUSION: In the earlier stages of focal cerebral infarction, blood-oxygen decreases while blood flow increases in the infarcted area. NIRS provides real-time, non-invasive monitoring of blood volume and blood-oxygen content in the cerebral tissue.