One-stage construction of giant experimental aneurysms in dogs

Preclinical extracranial aneurysm models for the study and treatment of brain aneurysms: A systematic review

Animal models make an important contribution to our basic understanding of the pathobiology of human brain aneurysms, are indispensable in testing novel treatment approaches, and are essential for training interventional neuroradiologists and neurosurgeons. Researchers are confronted with a broad diversity of models and techniques in various species. This systematic review aims to summarize and categorize extracranial aneurysm models and their characteristics, discuss advantages and disadvantages, and suggest the best use of each model. We searched the electronical Medline/PubMed database between 1950 and 2020 to identify main models and their refinements and technical modifications for creation of extracranial aneurysms. Each study included was assessed for aneurysm-specific characteristics, technical details of aneurysm creation, and histological findings. Among more than 4000 titles and abstracts screened, 473 studies underwent full-text analysis. From those, 68 different techniques/models in five different species were identified, analyzed in detail, and then grouped into one of the five main groups of experimental models as sidewall, terminal, stump, bifurcation, or complex aneurysm models. This systematic review provides a compact guide for investigators in selecting the most appropriate model from a range of techniques to best suit their experimental goals, practical considerations, and laboratory environment.

In vivo cerebral aneurysm models

Cerebral aneurysm rupture is a devastating event resulting in subarachnoid hemorrhage and is associated with significant morbidity and death. Up to 50% of individuals do not survive aneurysm rupture, with the majority of survivors suffering some degree of neurological deficit. Therefore, prior to aneurysm rupture, a large number of diagnosed patients are treated either microsurgically via clipping or endovascularly to prevent aneurysm filling. With the advancement of endovascular surgical techniques and devices, endovascular treatment of cerebral aneurysms is becoming the first-line therapy at many hospitals. Despite this fact, a large number of endovascularly treated patients will have aneurysm recanalization and progression and will require retreatment. The lack of approved pharmacological interventions for cerebral aneurysms and the need for retreatment have led to a growing interest in understanding the molecular, cellular, and physiological determinants of cerebral aneurysm pathogenesis, maturation, and rupture. To this end, the use of animal cerebral aneurysm models has contributed significantly to our current understanding of cerebral aneurysm biology and to the development of and training in endovascular devices. This review summarizes the small and large animal models of cerebral aneurysm that are being used to explore the pathophysiology of cerebral aneurysms, as well as the development of novel endovascular devices for aneurysm treatment.

Surgical options in experimental porcine model for endovascular training in complex vascular lesions

We describe a new, elegant, two-phase, microsurgical method that minimizes the surgical preparation time for different complex vascular lesions in a swine model. In the first phase, the model is prepared microsurgically in the experimental laboratory using arterial or/and venous grafts. In the second phase, the model is implanted in the experimental animal. This two-fold method allows for increasing the complexity and accuracy of the model while reducing preparation time on the day of the training session.

Stable experimental model of carotid artery saccular aneurysm in swine using the internal jugular vein

OBJECTIVE

To develop an experimental model of stable saccular aneurysm in carotid of pigs using the internal jugular vein.

METHODS

In 12 healthy pigs, weighing between 25 and 5 0kg, five males and seven females, we made a right common carotid artery aneurysm. After elliptical arteriotomy, we carried out a terminolateral anastomosis with the distal stump of the internal jugular vein. Aneurysm volume was calculated so that the value did not exceed 27 times the area of the arteriotomy. After six days angiography and microscopic examination were performed to assess patency of the aneurysm and the presence of total or partial thrombosis.

RESULTS

There was a significant weight gain of pigs in the time interval between the manufacture of the aneurysm and angiography (p = 0.04). Aneurysmal patency was observed in ten pigs (83%). Operative wound infections occurred in two animals (16.6%), both with early onset, three days after the making of the aneurysm. Histological analysis showed aneurysm thrombus partially occluding the light in nine pigs (75%). In these animals, it was observed that on average 9% of the aneurysmal diameter was filled with thrombi.

CONCLUSION

It was possible to develop a stable experimental model of saccular aneurysms in pig carotid artery by use of the internal jugular vein.

A large and giant bifurcation aneurysm model in canines: proof of feasibility

BACKGROUND AND PURPOSE

To our knowledge, no reproducible animal model of a giant bifurcation type aneurysm has been described. It was our aim to develop a 1-stage and reproducible model of a venous pouch giant aneurysm in canines.

MATERIALS AND METHODS

Nine canines were involved. Bilateral CCAs were exposed. The left CCA was divided and its distal segment was swung to the right side. Using the right CCA and the distal segment of the left CCA, either a bifurcation or a terminal arterial structure was constructed. Bilateral external jugular veins were also exposed. A 30-mm vein segment was harvested from each side. Each vein graft was split and unfolded to make 2 venous sheets. These sheets were then joined top-to-bottom so as to form a single cylinder in such a way that original adventitial side of the venous sheets was on the exterior surface. In 2 instances, pieces of polytetrafluoroethylene were employed along with the venous sheets. The combined vein graft was then incorporated into the arterial anastomosis. Lastly, the top of the venous pouch was closed. No medications for anticoagulant or antiplatelet were used throughout the study period. Follow-up imaging studies were performed.

RESULTS

It took 2.5 hours on average for 2 operators to create an aneurysm. Eight of the 9 aneurysms were patent at follow-up. The cause of the spontaneous thrombosis was unclear despite autopsy. All the aneurysms had a maximum diameter >20 mm.

CONCLUSIONS

We demonstrated and illustrated a 1-stage and reproducible procedure to create a model of a venous pouch bifurcation giant aneurysm in canines.

An animal model for femoral artery pseudoaneurysms

PURPOSE

To prepare a porcine model for femoral artery pseudoaneurysm via a one-step surgical procedure without the need for microsurgery.

MATERIALS AND METHODS

This pseudoaneurysm model involves the preparation of an arteriovenous shunt between the femoral artery and femoral vein in which approximately 2 cm of the vein is segmented by proximal and distal closure with the use of ligatures. The femoral pseudoaneurysm models were evaluated by angiography, Doppler auscultation, and histologic examination.

RESULTS

In seven of eight pigs, angiography and Doppler auscultation showed that the pseudoaneurysm models were open and that there was communication between the pseudoaneurysm model and the femoral artery. The mean length (+/-SD) of the pseudoaneurysm model was 1.9 cm +/- 0.3 (n= 7), with a neck region of 4 mm. Histologic analysis confirmed that pseudoaneurysm models were open and no thrombi were observed.

CONCLUSIONS

The principal advantages of this model are the location of the pseudoaneurysm model, the short period of clamping, and the controllable size. The pig pseudoaneurysm model is straightforward and reproducible, and may serve as a useful tool in the evaluation of interventional strategies for treatment of pseudoaneurysms.

Experimental modifications to a canine infrarenal aortic aneurysm model for the validation of endovascular stent-grafts: an exploratory study

The intraluminal elastase perfusion model has been proven to be potentially effective in producing abdominal aortic aneurysms (AAA) in rodents, yet has produced unpredictable results in larger animals. The purpose of this study was to explore different variations to an existing elastase perfusion model in the dog in the hopes of producing a consistent AAA for endovascular graft validation. The elastase perfusion canine model was modified as follows: (1) inflation of a balloon catheter in the infrarenal aorta (IA) of 3 dogs following elastase perfusion with doses of 2800 U for 40 min; (2) perfusion of the IA of 5 dogs with various elastase doses ranging from 2800 U to 8400 U for 2 h; and (3) perfusion of the IA of 2 dogs with elastase and collagenase for 2 h. The dogs were sacrificed at 4, 7, and 29 weeks. Prior to sacrifice, the treated aortic segments were either examined in vivo by x-ray angiography or by ultrasonography to measure aneurysmal dilation. The aortas were examined macroscopically postmortem to assess the luminal surface characteristics, and under light microscopy and scanning electron microscopy to reveal any pathological injuries induced by the various treatments on the aortic wall. Perfusion of the aorta with 2800 U elastase for 40 min followed by balloon catheter inflation either immediately or 3 weeks after perfusion produced no dilation. Perfusion for 2 h with either elastase alone or in combination with collagenase showed an increased aortic diameter averaging 65.6+/-20.8%, with an irregular dilation of the aortic wall. Histological examination revealed partially digested elastic network of the intima, media, and adventitia, as well as a reduction in the number of smooth muscle cells. An intimal hyperplasic reaction was observed in some of the dogs. Located sparingly within the intima were extravasated erythrocytes associated with recent hemorrhages, intramural thrombi in reorganization, and occasional necrotic lesions. The various modifications brought to the elastase perfusion model failed to produced an aneurysmal dilation with enough expansion to make it a reliable model for endovascular graft validation.

Experimental saccular aneurysms. I. Review of surgically-constructed models and their laboratory applications

Experimental models of intracranial saccular aneurysms are a useful contribution to our basic understanding of these lesions. Currently, the commonest in use are those constructed surgically in laboratory animals. We review the numerous surgical techniques available since the 1950s, and the research applications and uses of experimental aneurysms. Further development and use of such models is greatly encouraged in future pathophysiological, hemodynamic, and therapeutic investigations of intracranial saccular aneurysms.