Improved microsurgical creation of venous pouch arterial bifurcation aneurysms in rabbits

Abstract

Background and purpose: The choice of the experimental aneurysm model is essential for valid embolization-device evaluations. So far, the use of the rabbit venous pouch arterial bifurcation aneurysm model has been limited by demanding microsurgery, low aneurysm patency rates, and high mortality. This study aimed to facilitate microsurgery and to reduce mortality by optimized peri-/postoperative management.

Materials and methods: Aneurysms were created in 16 New Zealand white rabbits under general intravenous anesthesia. Using modified microsurgical techniques, we sutured a jugular vein pouch into a bifurcation created between both CCAs. Aggressive anticoagulation (intraoperative intravenous: 1000-IU heparin, 10-mg acetylsalicylic acid/kg; postoperative subcutaneous: 14 days, 250-IU/kg /day heparin) and prolonged postoperative anesthesia (fentanyl patches: 12.5 μg/h for 72 hours) were applied. Angiographic characteristics of created experimental aneurysms were assessed.

Results: The reduced number of interrupted sutures and aggressive anticoagulation caused no intra-/postoperative bleeding, resulting in 0% mortality. Four weeks postoperation, angiography showed patency in 14 of 16 aneurysms (87.5%) and Ohshima type B bifurcation geometry. Mean values of parent-artery diameters (2.3 mm), aneurysm lengths (7.9 mm), and neck widths (4.1 mm) resulted in a mean 1.9 aspect ratio.

Conclusions: Compared with historical controls, the use of modified microsurgical techniques, aggressive anticoagulation, and anesthesia resulted in higher aneurysm patency rates and lower mortality rates in the venous pouch arterial bifurcation aneurysm model. Gross morphologic features of these aneurysms were similar to those of most human intracranial aneurysms.

Fig 1.

Microsurgical steps during venous pouch arterial bifurcation aneurysm creation. A, Suturing sequence at the posterior aspect of the anastomosis: 1) right to left CCA, 2) venous pouch to left CCA, 3) venous pouch to right CCA. B, Suturing sequence at the anterior aspect: 4) right to left CCA, 5) venous pouch to left CCA, 6) venous pouch to right CCA.

Fig 2.

Morphology of the venous pouch arterial bifurcation aneurysm. A, View under the operation microscope after microsurgery. B, Calibrated DSA 4 weeks after operation. A, 1) Proximal left CCA, 2) right CCA, 3) distal left CCA. Asterisk indicates the dome of the venous pouch aneurysm; the plus sign, the fat pad for sealing the suture line. B, DSA shows the aneurysm and parent-vessel patency after 4 weeks. Green lines indicate the aneurysm neck width and aneurysm length and the contour of the in-flow parent-artery (left CCA). Red line shows the distance of the neck plane center from the parent-artery contour.