Microsurgically induced aneurysm models in rats, part I: techniques and histological examination

The percentage of aneurysms treated surgically has steadily decreased since the results of the ISAT study were published in 2002. The aim of this study was to develop different reliable and reproducible aneurysm models for microsurgical training and further research to guarantee effective instruction in microsurgery for young neurosurgeons with comparable aneurysms like in humans.

Arterial and venous pouch aneurysm models were created microsurgically using 22 Wistar rats. The femoral and the proximal iliac vessels and the bifurcation of the common carotid artery were exposed for induction. For histological examination every aneurysm was dissected out and analysed.

A total of 39 microaneurysms was created in three different regions. During the creation four complications occurred: 4 bleedings and 1 defect were observed and immediately treated. Linear regression curves of the microsurgical evaluation showed a significant advancement in the course of the study. The volumes of the different models were: 2.58+/-1.01 mm (3) for the carotid, 6.49+/-3.36 mm (3) for the iliac and 10.41+/-4.13 mm (3) for the femoral aneurysms. The aspect ratios were 1.86+/-0.45 at the iliac, 1.62+/-0.3 at the femoral and 1.21+/-0.29 for the carotid aneurysms. In 89.7% of the cases the aneurysm sac was thrombosed accentuated at the aneurysm tip while the central zone of blood inflow revealed no thrombus formation. The proportion of endothelial cells displayed a reduction in relation to the total number per cross-section in all aneurysm types.

The presented aneurysm models in rats are reliably and immediately available for further training or scientific histological investigations. Despite the fact that these are not bifurcation aneurysms, basic techniques such as suturing and microtechniques used for the dissection and repair of vessels can be taught.