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Creation of Two Saccular Elastase-Digested Aneurysms with Different Hemodynamics in One Rabbit

Published: April 15th, 2021



1Department of Neurosurgery, Kantonsspital Aarau, 2Cerebrovascular Research Group, Department for BioMedical Research, University of Bern, 3Experimental Surgery Facility, Department for Biomedical Research, Faculty of Medicine, University of Bern

This protocol describes the steps for the creation of a rabbit model with two elastase-digested aneurysms with different hemodynamics (stump and bifurcation constellation). This allows the testing of novel endovascular devices in aneurysms with different angioarchitecture and hemodynamic conditions within a single animal.

Preclinical animal models with hemodynamic, morphologic, and histologic characteristics close to human intracranial aneurysms play a key role in the understanding of the pathophysiological processes and the development and testing of new therapeutic strategies. This study aims to describe a new rabbit aneurysm model that allows the creation of two elastase-digested saccular aneurysms with different hemodynamic conditions within the same animal.

Five female New Zealand white rabbits with a mean weight of 4.0 (± 0.3) kg and mean age of 25 (±5) weeks underwent microsurgical stump and bifurcation aneurysm creation. One aneurysm (stump) was created by right common carotid artery (CCA) exposure at its origin at the brachiocephalic trunk. A temporary clip was applied at the CCA origin and another, 2 cm above. This segment was treated with a local injection of 100 U of elastase for 20 min. A second aneurysm (bifurcation) was created by suturing an elastase-treated arterial pouch into the end-to-side anastomosis of the right CCA to left CCA. Patency was controlled by fluorescence angiography immediately after creation.

The average duration of surgery was 221 min. The creation of two aneurysms in the same animal was successful in all rabbits without complication. All aneurysms were patent immediately after surgery except for one bifurcation aneurysm, which showed an extreme tissue reaction due to elastase incubation and an immediate intraluminal thrombosis. No mortality was observed during surgery and up to one-month follow-up. Morbidity was limited to a transient vestibular syndrome (one rabbit), which recovered spontaneously within one day.

Demonstrated here for the first time is the feasibility of creating a two-aneurysm rabbit model with stump and bifurcation hemodynamic characteristics and highly degenerated wall conditions. This model allows the study of the natural course and potential treatment strategies on the basis of aneurysm biology under different flow conditions.

Intracranial aneurysm is a severe condition with a mortality rate after rupture reaching 50% and long-term disability in 10-20% of patients1. The last decade has seen a rapid development of endovascular treatment options but, at the same time, also an increasing rate of recurrence with up to 33% of aneurysm recanalization after coiling2,3. To better understand the pathophysiology underlying aneurysm occlusion and recanalization, as well as for the development and testing of new endovascular devices, there is currently a need for reliable preclinical models whose hemodynamic, morphologic....

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NOTE: The experiment was approved by the Local Committee for Animal Care of the Canton Bern, Switzerland (Application Number BE108/16), and all animal care and procedures were performed in accordance with institutional guidelines and 3R principles15,16. Data are reported according the ARRIVE guidelines. Peri-operative management was conducted by a board-certified veterinarian anesthesiologist. For the study, female New Zealand white rabbits, with a mean weight of.......

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The creation of a stump and a bifurcation aneurysm was successful in all 5 New Zealand white rabbits without intraoperative complications. No mortality was observed during surgery or during the follow-up period of 24 ± 2 days. One rabbit experienced postoperative complications with a vestibular syndrome and a blindness of the right side. The animal recovered completely and spontaneously after 24 h. This complication did not interfere with its normal activities (free movements, water and food intake, interactions wit.......

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The most common technique for aneurysm creation involves the creation of a stump aneurysm at the origin of the right CCA, either through an open or an endovascular method. The model has been validated to be a stable non-growing aneurysm that remains open with time20,21. The second possible technique involves the microsurgical creation of an arterial bifurcation aneurysm by anastomosing the right CCA on the left one and suturing an aneurysm pouch on the bifurcatio.......

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The authors thank Prof Hans Rudolf Widmer, Dr Luca Remonda, and Prof Javier Fandino for their scientific support and technical contribution to this work. A special thanks to Olgica Beslac for her advice during the procedures and Kay Nettelbeck for his assistance. Furthermore, we thank Daniela Casoni DVM, PhD and med. vet. Luisana Garcia, PD Dr Alessandra Bergadano, and Dr Carlotta Detotto for their dedicated veterinary support.


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Name Company Catalog Number Comments
4-0 resorbable suture Ethicon Inc., USA VCP292ZH
4-0 resorbable suture Ethicon Inc., USA VCP304H
6-0 non absorbable suture B. Braun, Germany C0766070
9-0 non absorbable suture B. Braun, Germany G1111140
Adrenaline Amino AG 1445419 any generic
Amiodarone Helvepharm AG 5078567 any generic
Anesthesia machine Dräger any other
Aspirin Sanofi-Aventis (Suisse) SA 622693 any generic
Atropine Labatec Pharma SA 6577083 any generic
Bandpass filter blue Thorlabs FD1B any other
Bandpass filter green Thorlabs FGV9 any other
Biemer vessel clip (2x) B. Braun Medical AG, Aesculap, Switzerland FD560R any other
Bipolar forceps any other
Bispectral index (neonatal) any other
Blood pressure cuff (neonatal) any other
Bycilces spotlight any other
Clamoxyl GlaxoSmithKline AG 758808 any generic
Dexmedetomidine Ever Pharma 136740-1 any generic
Elastase Sigma Aldrich E7885
Electrocardiogram electrodes
Ephedrine Amino AG 1435734
Esmolol OrPha Swiss GmbH 3284044
Fentanyl (intravenous use) Janssen-Cilag AG 98683
Fentanyl (transdermal) Mepha Pharma AG 4008286
Fluoresceine Curatis AG 5030376
Fragmin Pfizer PFE Switzerland GmbH 1906725
Heating pad or heating forced-air warming system
Isotonic sodium chloride solution (0.9%) Fresenius KABI 336769
Ketamine Pfizer PFE Switzerland GmbH 342261
lid retractor Approach
Lidocaine Streuli Pharma AG 747466
Metacam Boehringer Ingelheim P7626406 Medication
Methadone Streuli Pharma AG 1084546 Sedaton
Micro-forceps  curved Ulrich Swiss, Switzerland U52-015-15
Micro-forceps  straight 2x Ulrich Swiss, Switzerland U52-010-15
Microscissors Ulrich Swiss , Switzerland U52-327-15
Midazolam Accord Healthcare AG 7752484
Needle 23 G arteriotomy
Needle holder
O2-Face mask
Operation microscope Wild Heerbrugg
Papaverin Bichsel topical application
Povidone iodine Mundipharma Medical Company any generic
Prilocaine-lidocaine creme Emla
Propofol B. Braun Medical AG, Switzerland General anesthesia
Pulse oxymeter
Rectal temperature probe (neonatal)
Ringer Lactate Bioren Sintetica SA Infusion
Ropivacain Aspen Pharma Schweiz GmbH 1882249 Local anesthesia
Scalpell Swann-Morton 210
Small animal shaver
Soft tissue forceps
Soft tissue spreader
Stainless steel sponge bowls
Sterile micro swabs
Surgery drape
Surgical scissors
Syringes 1 mL, 2 mL, and 5 mL
Tris-Buffer Sigma Aldrich 93302 Elastase solution
Vascular clip applicator B. Braun, Germany FT495T
Vein and arterial catheter 22 G
vessel loop Approach
video camera or smartphone
Vitarubin Streuli Pharma AG 6847559
Yasargil titan standard clip (2x) B. Braun Medical AG, Aesculap, Switzerland FT242T

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