Microsurgical Venous Pouch Arterial-Bifurcation Aneurysms in the Rabbit Model: Technical Aspects

Summary

An optimized technique for the microsurgical creation of arterial bifurcation aneurysms mimicking bifurcation human cerebral aneurysms is described. A venous pouch is sutured into an artificially created true bifurcation of both common carotid arteries. Facilitated microsurgical techniques and aggressive postoperative anticoagulation and analgesia lead to minimized morbidity rates and high aneurysm patency rates.

Abstract

For ruptured human cerebral aneurysms endovascular embolization has become an equivalent alternative to aneurysm clipping.¹ However, large clinical trials have shown disappointing long-term results with unacceptable high rates of aneurysm recanalization and delayed aneurysm rupture.² To overcome these problems, animal experimental studies are crucial for the development of better endovascular devices.^3-5

Several animal models in rats, rabbits, canines and swine are available.^6-8 Comparisons of the different animal models showed the superiority of the rabbit model with regard to hemodynamics and comparability of the coagulation system and cost-effectiveness.^9-11

The venous pouch arterial bifurcation model in rabbits is formed by a venous pouch sutured into an artificially created true bifurcation of both common carotid arteries (CCA). The main advantage of this model are true bifurcational hemodynamics.¹² The major drawbacks are the sofar high microsurgical technical demands and high morbidity and mortality rates of up to 50%.¹³ These limitations have resulted in less frequent use of this aneurysm model in the recent years. These shortcomings could be overcome with improved surgical procedures and modified peri- and postoperative analgetic management and anticoagulation.^14-16 Our techniques reported in this paper demonstrate this optimized technique for microsurgical creation of arterial bifurcation aneurysms.

Protocol

1. Positioning and preparation of the animal

The experiments were approved by the responsible local ethical committee and performed according to the Felasa guidelines.

1. Start general anesthesia of the female New Zealand White rabbit (2.5-3.5 kg) with intramuscular injection of Ketamin (30mg/kg) and Xylazine (6mg/kg) and continue after mechanical intubation (tube diameter 4mm, length 18mm) with gas anesthesia (Isoflurane) under ECG monitoring. Perform pain monitoring via toe pinch all 15 minutes and adapt anesthesia in case of positive response.
2. Fix the rabbit in supine position on a bodywarm plate.
3. Pr....

Discussion

The authors recommend to considerate the following critical surgical key steps to achieve good results and patent aneurysms:

1. Careful dissection of a long segment of the left CCA for easy anastomosis without destruction of nerves and small vessels.
2. Careful removal of the highly thrombogenic periadventitial fibrous tissue prior to the creation of the anastomosis.
3. Creation of a tensionless anastomosis.
4. Fewer sutures: The proposed sequence of anastomsis sites beginning at the back.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Vicryl4-0 polyfilament restorable sutures	Ethicon Inc.	J386H
Ethilon 10-0 monofil non resorbable sutures	Ethicon Inc.	2814	taper point needle
Evicel Bioglue	Ethicon Inc.	3901
Fentanyl dermal patch 12.5 μg/h			Any genericon
Heparin			Any genericon
0.9% Saline			Any genericon
4% Papaverin HCl			Any genericon
Neomycin sulfate 5 mg/ml			Any genericon
Ketamin 50mg/ml			Any genericon
Xylazine 20mg/ml			Any genericon