In Vivo Experimental Intracranial Aneurysm Models: A Systematic Review

Abstract

SUMMARY: Animal models are necessary to develop and test innovations in aneurysm therapy before clinical introduction. This review aims at identifying the most likely candidates for standardizing preclinical testing of aneurysm devices. We systematically searched electronic databases for publications on animal aneurysm models from 1961-2008 to assess the methodologic quality of the studies and collect data on the patency and angiographic and pathologic outcomes of treatments. There has been a steady increase in the annual number of publications with time. Species that were most frequently used were dogs, rabbits, and rodents, followed by swine. Most publications are single-laboratory studies with variables and poorly validated outcome measures, a small number of subjects, and limited standardization of techniques. The most appropriate models to test for recurrences after endovascular occlusion were the surgical bifurcation model in dogs, and the elastase-induced aneurysm model in rabbits. A standardized multicenter study is needed to improve the preclinical evaluation of endovascular devices in aneurysm therapy.

Retrieval of Migrated Coils with Stent Retrievers: An Animal Study

“…Even though data from an animal model cannot be transferred to humans without restrictions (eg, that peripheral swine vessels might be less susceptible to perforations compared with human cerebral vessels or that our swine model did not allow detection of thrombotic emboli), swine represent an established animal model for endovascular procedures, given their comparable vascular anatomy and coagulation. 28 To anticipate differences between humans and swine, we examined coil retrieval in vessels that are comparable with affected human vessels with regard to size, blood flow, and accessibility. A further limitation is that an experiment that involves all possible combinations of coils, vessels, and stent retrievers is practically impossible.…”

Improved Microsurgical Creation of Venous Pouch Arterial Bifurcation Aneurysms in Rabbits

“…21 In general, arterial sidewall aneurysm models cannot predict the ability of new coils to improve long-term angiographic results under more challenging hemodynamic conditions. 6 For example, it was shown by computer-assisted morphometric comparison of various aneurysm models that bare platinum coils performed equally as well as HydroCoils (MicroVention Terumo, Aliso Viejo, California) only in a canine arterial sidewall aneurysm model, while in arterial bifurcation models, HydroCoils provided better long-term stable occlusion. 18 In contrast, the venous pouch arterial bifurcation model is created by a venous pouch sutured into an artificial true bifurcation of both CCAs.…”

“…The postulated main advantages of this model are true bifurcational hemodynamics 21 and the possibility of varying the anatomy of the bifurcation and neck/fundus size of the aneurysm. 6 The postulated histomorphologic drawback is a supposed pronounced foreign body reaction around the suture lines at the neck plane, impairing thrombus organization and fibrovascular healing. 10 However, it has already been shown that the foreign body response to the monofilament sutures around the anastomosis is only benign and that this chronic inflammatory reaction to nonresorbable sutures is locally confined to the outer parts of the respective vessel walls.…”

“…[3][4][5] The choice of the model is essential for the comparability of experimental findings with human conditions. 6 In a comparison of the currently used animal models in rats, rabbits, canines, and swine, [7][8][9] the rabbit model showed advantageous comparability with the human coagulation system and the best cost-effectiveness. [10][11][12] At the moment, the most frequently used aneurysm model is the rabbit elastase model, [13][14][15] based on intraluminal perfusion of the stump of 1 CCA with pancreatic elastase.…”

“…Thus the major limitation of this aneurysm model 6 was apparently overcome. Despite the small number of animals who underwent surgery, this favorable mortality rate is comparable with the 8.4% mortality reported by Lewis et al 29 during elastase aneurysm creation in an extremely large series of 700 rabbits undergoing surgery.…”