A modified method of elastase-induced saccular aneurysm creation in rabbits: Schematic representation of the method

Abstract

Background: The purpose of our study was to investigate the safety and effectiveness of a modified technique using a short guiding catheter for instillation of elastase in comparison with the previously described method of creating elastase-induced aneurysm in rabbits.

Methods: Following right common carotid artery (RCCA) access using an arterial sheath and inflating the Fogarty balloon in the subclavian artery, a short guiding catheter was used for the instillation of the elastase in the experimental group (n = 5) while it was performed with a microcatheter in the control group (n = 5). The procedure duration was recorded from the RCCA puncture to the sheath removal. The histological changes were characterized using H&E and Masson's trichrome (MT) staining.

Results: The procedure time was 23 ± 2 min in the experimental group and 29 ± 2 min in the control group. All the rabbits (100%) in the experimental group survived without neurologic deficits, but two rabbits (40%) survived in the control group. All aneurysms were created in the saccular shape (100%) with a neck size of 2.3 ± 0.29 mm, a width of 2.75 ± 0.36 mm, and height of 6.37 ± 0.46 mm, and a dome to neck ratio of 1.21 ± 0.23. The aneurysm walls were partly thickened due to the degradation of the media tunica and adventitia proliferation with loss of the internal elastic lamina.

Conclusion: By using a short guiding catheter, we could instill the elastase in a more effective and safe manner in the creation of the elastase-induced aneurysm model in rabbits.

Keywords: Elastase; aneurysm model; animal model; saccular aneurysm; vascular disorder.

Figure 1.

Illustration and radiographic images showing the technical steps for the elastase-induced aneurysm model. (a) Preparing to tie the right common carotid artery (RCCA) using two 4-0 black silk threads and puncture the RCCA using a 18G Teflon-sheath needle (black arrowhead). (b) The sheath (white arrowhead) is placed in a retrograde manner to RCCA. (c) 4-0 black silk threads placed on the proximal RCCA are tied once to fix the sheath (black arrow). Subsequently, the short guiding catheter (yellow arrow) and rotating hemostasis valve (RHV) (blue arrow) are advanced. (d) The digital subtraction angiography (DSA) is performed to check the vessels. (e) The balloon is inserted via a guiding catheter with RHV. (f) The target site is identified using a contrast media (white arrow) to completely obstruct the subclavian artery and brachiocephalic artery with a balloon. (g) The elastase (green arrow) is induced in the isolated RCCA segment and at the same time blood is drawn out through the valve of the sheath. (h) The schematic images of the saccular aneurysm at the RCCA and (i) representative DSA images of created elastase-induced aneurysm in the rabbit.

Figure 2.

Complications due to elastase leakage. (a) Pus (arrowhead) accumulation all over the subcutaneous and (b) an abscess (star) formed along the right common carotid artery (RCCA). (c) The RCCA is dissected with an abscess.

Figure 3.

Representative digital subtraction angiography (DSA) and microscopic histological images of created aneurysms in rabbit. (a-e) The control group. (a) DSA image. (b) Hematoxylin & eosin (H&E) images of the aneurysmal dome (black dotted line) and (c) magnified aneurysmal wall (black line). (d) Masson's trichrome (MT) images of the middle portion of the aneurysm (yellow dotted line) and (e) magnified aneurysmal wall (yellow line). (f–j) The experimental group. (f) DSA image. (g) H&E images of the aneurysmal dome (black dotted line) and (h) magnified aneurysmal wall (black line). (i) MT images of the middle portion of the aneurysm (yellow dotted line) and (j) magnified aneurysmal wall (yellow line). The aneurysms in both groups demonstrated an abnormal vessel wall with neointimal and uneven tunica media as well as partial destruction of the internal elastic lamina. In addition, elastic fibers with the destruction of the internal elastic lamina were observed, but no inflammatory reaction was noted (Magnification: ×20.6).