Interval change in size of venous pouch canine bifurcation aneurysms over a 10-month period

BACKGROUND AND PURPOSE: The natural history study of experimental aneurysms is important for the evaluation of new endovascular occlusion devices. Our purpose was to evaluate the natural history of experimental venous pouch bifurcation aneurysms in mongrel dogs up to a 10-month period. MATERIALS AND METHODS: Serial digital subtraction angiography was performed in 5 bifurcation aneurysms 1, 4, 7, and 10 months after surgical creation. Aneurysm dimensions, including height, width, and neck diameter, and animal body weights were measured. Comparisons of each parameter were performed using the Friedman test and the paired Wilcoxon signed-rank test. RESULTS: Four of 5 aneurysms were patent during a 10-month follow-up period. One aneurysm was regarded as a partially thrombosed aneurysm at 1 month, though the extent of partial thrombosis lessened at 10 months. Bifurcation aneurysms progressively increased in size (aneurysm height, width, and neck diameter) during the first several months. CONCLUSION: If this experimental model is used to evaluate new endovascular devices for cerebral aneurysm treatment, investigators should be aware of early progressive aneurysm enlargement.