RAPID SACCULAR ANEURYSM INDUCTION BY ELASTASE APPLICATION IN-VITRO

OBJECTIVE: To develop a new saccular aneurysm model in vitro using ela stase to study aneurysm initiation, growth, and rupture and to create a new in vivo aneurysm model to test endovascular therapies. METHODS: Seventeen common carotid arteries excised from freshly killed pigs and sheep were treated with seven different methods of elastase delivery. The arteries were mounted in a saline-filled flow chamber. They recei ved pulsatile flow for 48 hours, or until the resulting aneurysms rupt ured. Changes were continuously monitored with video camera recordings and validated with histological sections. RESULTS: All eight arteries treated topically, either on the intimal or on the adventitial surfac e, with elastase concentrations greater than 1 U/mm(2), developed sacc ular aneurysms; five of them ruptured within 48 hours. All four arteri es treated with surface concentrations of 0.1 U/mm(2) via microcathete r infusion into the lumen developed fusiform aneurysms. None of the ar teries that received surface concentrations less than 0.1 U/mm(2) deve loped aneurysms. Histological sections revealed a reduced number of ce llular elements in a stretched collagen matrix at the dome of the sacc ular aneurysms. CONCLUSION: After empirically testing several methods of elastase delivery, we were able to induce saccular, bifurcation-typ e aneurysms in animal arterial specimens. These aneurysms are histolog ically similar and more authentic than surgical models. The procedure is easy and reproducible. Our results suggest a possible enzymatic rol e in aneurysm formation and highlight the dramatic effects of selectiv e arterial elastic damage. Also, the rapid growth of our experimental aneurysms may reflect the speed of the natural process.