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.
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.
1. Positioning and preparation of the animal
The experiments were approved by the responsible local ethical committee and performed according to the Felasa guidelines.
2. Preparation of the external jugular vein
3. Preparation of both common carotid arteries (CCAs)
4. Anastomosis of both CCAs
5. Postoperative management
6. Representative Results:
If the procedure is done correctly, the aneurysm will stay patent and the animals will recover within about 3 days. In our experience an imaging procedures should be done at minimum one week later. Otherwise the animals possibly won’t tolerate the procedure and could be lost. For embolization we would recommend to wait for about 4 weeks to guarantee complete endothelialization of the aneurysm neck.Using the presented techniques and management the authors could reach aneurysm patency in 85.7% and no mortality in their recently published series.14 To minimize the high rate of reported intestinal complications of up to 20%,12 we provided a prolonged postoperative analgetic management of 72 hour analgesia as compared to routine 24 hour analgesia.This intensified management resulted in no gastric complications. The aggressive anticoagulation management is important to reach sufficient aneurysm patency rates. This goes along with the findings of Grunwald et al. showing the positive effects of combined anticoagulation.17 Because of the aggressive anticoagulation it is crucial to have an effective sealing of the anastomosis. We made very good experience using new fibrin glue (Evicel, Ethicon Biosurgery Inc., New Jersey, USA). Additionally we recommend using small rabbits (maximum 3.5 kg), as in our experience complications are often related to overweight subjects.
The authors recommend to considerate the following critical surgical key steps to achieve good results and patent aneurysms:
Figure 1. Intraoperative microscopic photos.
The authors have nothing to disclose.
This study was supported by the ‘Medical Scientific Fund of the Major of the City of Vienna’ and Ethicon Biosurgery, Inc. New Jersey, USA. The authors express their thanks to Professor Heber Ferraz-Leite, Director of the ‘European Workshop on Microsurgery and Cerebral Revascularization’ at the Medical University of Vienna, Austria, for his valuable microsurgical teaching.
Name of the reagent | Company | Catalogue 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 Biosurgery 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 |