[Re-evaluation of an embolic material for aneurysm cellulose acetate polymer]

To re-evaluate the safety, effect, and pathological reactions of cellulose acetate polymer (CAP).

30 right carotid arteries of rats were embolized and got two embolized vessels for histological study in each of the seven stages within four months. Fifteen canine aneurysmal models were created by transplantation of venous pouches. Twelve of them were occluded with CAP. Digital Subtraction Angiography (DSA) follow-ups of occluded aneurysmal models were carried out 1, 2 and 8 weeks after occlusion. One animal was sacrificed randomly at each stage for pathological study.

Only five of the 12 aneurysmal models were completely or partially occluded within the patency of parent arteries within two months of observation after embolization with CAP. Stenosis of one branch of aneurysmal parent artery was occurred. The residual cavity of one partially occluded model artery was enlarged. Two models ruptured on four and five days after embolization. Three embolized models and their parent arteries were all occluded.

acute pathological reaction occurred within vessels embolized with CAP. Endothelial cell and basal membrane were damaged and vanished. Elastic lamina was exposed to arterial lumen and attached by thrombus layer. Fibrous cells and smooth muscle cells showed obvious degeneration. CAP and thrombus were gradually organized in two months after thrombosis. The orifices of aneurysmal models were covered with newly developed fibrous tissue and endothelial cells in two months after thrombosis.

We think that acute chemical erosive effect of CAP was evident. A strong effect could lead to rupture of some of the CAP thrombosed aneurysmal models. Besides, stenosis or occlusion of the parent arteries could be induced in some cases after embolization with CAP. For the above shortcomings and limitations, it should be improved carefully before it is applied in clinic.