Healing response in elastase-induced rabbit aneurysms after embolization with a new platinum coil system.
OBJECTIVE
Elastase-induced rabbit aneurysms offer promise in preclinical testing, but their radiographic and histologic features after dense packing with platinum coils are unknown. We evaluated these features by using a new platinum coil system.


METHODS
Right common carotid arterial (CCA) aneurysms were created in 17 rabbits by distal ligation and intraluminal elastase incubation. At least 3 weeks later, aneurysms were packed with detachable platinum coils. Animals were sacrificed at 2 (group 1, n=4), 4 (group 2, n=5), 12 (group 3, n=4), or 24 (group 4, n=4) weeks. Aneurysmal occlusion and coil compaction were angiographically assessed. Histologic features of tissue covering the coils and the aneurysmal dome were assessed and semiquantitatively compared across groups.


RESULTS
No notable tracking, deployment, or detachment problems occurred. Volumetric occlusion was 5-49% (mean, 26.8% +/- 11%). Angiographic occlusion was 100% in six cases, 95% in four, and 90% in seven; occlusion scores remained unchanged in 13 cases, decreased in one, and increased in two (one case excluded from angiographic follow-up). Histologic findings were concordant within groups. Group 1 had coverage with thin fibrin layers and scattered leukocytes; group 2, some spindle-cell coverage; group 3, spindle-cell coverage. In groups 1 and 2, dome findings included only unorganized blood products. In group 3, blood products had been replaced with a hypocellular, poorly staining matrix. Some group 4 subjects had variably aged blood products, with tissue of limited organization.


CONCLUSIONS
The platinum coil system performed well in experimental aneurysmal embolization. Densely packed rabbit aneurysms demonstrate reproducible histologic evolution: early fibrin coverage, delayed spindle-cell coverage, delayed intraaneurysmal thrombus resorption, and occasional coil compaction.
Fujiwara
Naomi H
NH
Department of Radiology, University of Virginia Health Services, Charlottesville 22908, USA.
Kallmes
David F
DF
D000818:Animals; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D004195:Disease Models, Animal; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D004867:Equipment Design; D004869:Equipment Safety; D005500:Follow-Up Studies; D002532:Intracranial Aneurysm / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010196:Pancreatic Elastase / Q000009:adverse effects*; D010984:Platinum / Q000627:therapeutic use*; D011817:Rabbits; D011859:Radiography; D014945:Wound Healing / Q000502:physiology*
D010984:Platinum; D010196:Pancreatic Elastase