Angiographic investigation of orbital vascular variations in the rabbit and implications for endovascular intra-arterial chemotherapy models.

Abstract

The New Zealand White rabbit (NZWR) is the first small-animal experimental model of intra-arterial chemotherapy (IAC) for retinoblastoma treatment. The NZWR has dual ophthalmic arteries (OA): the external OA (EOA) arises from the external carotid artery and the internal OA (IOA) from the internal carotid artery. We describe the technique that we have refined for OA catheterization in rabbits, and describe the angioanatomical variations in the OA supply to the NZWR eye and implications for IAC delivery, which were identified as part of a larger project exploring IAC effects in a rabbit retinoblastoma model. We developed techniques to perform angiography of the external and internal carotid arteries and superselective angiography of the EOA and IOA in NZWR using transfemoral access and a microwire/microcatheter system. EOA and IOA supply to the eye was determined angiographically and recorded before selective OA catheterization and angiography. 114 rabbits underwent carotid angiographic evaluation and OA catheterization (161 total eyes evaluated, 112 right, 49 left). Most eyes had a single dominant arterial supply; either IOA or EOA. EOA was dominant in 73% (118/161), and IOA was dominant in 17% (27/161). Co-dominant supply was seen in 10% (16/161). Of the rabbits with bilateral OA catheterization, 25/47 (53%) had bilateral dominant EOA. Successful catheterization of the OA in the NZWR can be readily accomplished with nuanced technique. The external OA is the dominant arterial supply in the majority of NZWR eyes. These findings allow for successful reproduction of OA catheterization studies of IAC for retinoblastoma in NZWR.