Testing flow diversion in animal models: a systematic review

Flow diversion (FD) is increasingly used to treat intracranial aneurysms. We sought to systematically review published studies to assess the quality of reporting and summarize the results of FD in various animal models.

Databases were searched to retrieve all animal studies on FD from 2000 to 2015. Extracted data included species and aneurysm models, aneurysm and neck dimensions, type of flow diverter, occlusion rates, and complications. Articles were evaluated using a checklist derived from the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines.

Forty-two articles reporting the results of FD in nine different aneurysm models were included. The rabbit elastase-induced aneurysm model was the most commonly used, with 3-month occlusion rates of 73.5 %, (95 %CI [61.9–82.6 %]). FD of surgical sidewall aneurysms, constructed in rabbits or canines, resulted in high occlusion rates (100 % [65.5–100 %]). FD resulted in modest occlusion rates (15.4 % [8.9–25.1 %]) when tested in six complex canine aneurysm models designed to reproduce more difficult clinical contexts (large necks, bifurcation, or fusiform aneurysms). Adverse events, including branch occlusion, were rarely reported. There were no hemorrhagic complications. Articles complied with 20.8 ± 3.9 of 41 ARRIVE items; only a small number used randomization (3/42 articles [7.1 %]) or a control group (13/42 articles [30.9 %]).

Preclinical studies on FD have shown various results. Occlusion of elastase-induced aneurysms was common after FD. The model is not challenging but standardized in many laboratories. Failures of FD can be reproduced in less standardized but more challenging surgical canine constructions. The quality of reporting could be improved.