ENDOVASCULAR OCCLUSION OF EXPERIMENTAL ANEURYSMS WITH DETACHABLE COILS - INFLUENCE OF PACKING DENSITY AND PERIOPERATIVE ANTICOAGULATION

OBJECTIVE: This study was designed to assess the intraluminal biologic al changes after endovascular coil occlusion of arterial aneurysms wit h detachable coils, to analyze the relationship between histological o cclusion and mechanical packing density, and to evaluate the influence of perioperative anticoagulation on the occlusion rate. METHODS: In r abbits, 30 microsurgically produced arterial bifurcation aneurysms wer e occluded with coils (18 with platinum coils, electrically detached; 12 with tungsten coils, mechanically detached). Coils were placed unti l no further coils fit into the aneurysmal lumen and it was no longer filled with radiographic contrast material. The individual degree of o cclusion was then determined by the ''packing density'' on the angiogr ams. Complete occlusion was considered only if no neck remnant was vis ible on the films. Anticoagulation during and 2 days after the treatme nt was performed in 11 cases. After an observation period ranging from 3 to 6 months, angiographic and histological analyses were performed to obtain control data. RESULTS: Complete occlusion was achieved in 9 cases, subtotal occlusion (i.e., >95% occlusion, residual filling at t he neck of the aneurysm) in 10 cases, and partial occlusion in 11 case s. Angiographically documented recanalization was detected in 14 aneur ysms. In the remaining 16 aneurysms, the initially documented angiogra phic results were unchanged. A discrepancy between angiographic and pa thological findings was frequently observed. Five of nine angiographic ally completely occluded aneurysms were recanalized. Endothelial-like tissue at the orifice of the aneurysm was able to be observed in only four of the nine initially completely occluded aneurysms. CONCLUSION: The results suggest that even dense packing does not always guarantee permanent occlusion, although there was a positive relationship betwee n packing density and occlusion rate. Anticoagulation did not have any negative effect on the results.