An Increment in Unilateral Carotid Blood Flow Produces Cerebral Aneurysms in Rats

Summary

To study the effect of haemodynamic stress on cerebral aneurysm development, three groups of adult Wistar rats were used: 1) One group with ligation of the right common carotid artery; 2) One with an end-to-side common carotid artery anastomosis and 3) Another group that was sham-operated. Blood flow through the left common carotid artery was measured with an electromagnetic flow transducer (0.85 mm in diameter) in anesthetized animals. Before the experimental intervention, the mean carotid blood flow was 2.8 ± 0.14 ml/min. Following carotid ligation the blood flow in the patent carotid artery increased 25 ± 5% after 7 ± 0.3 days and 37 ± 18% after 149 ± 23 days; whereas following carotid anastomosis, carotid blood flow increased 102 ± 16% after 9.6 ± 2 days and 103 ± 35% after 169 ± 15 days. The sham operation did not significantly affect carotid blood flow. Control values for mean arterial pressure (102 ± 3 mmHg) and blood gases (PaO₂ = 106 ± 3 4 mmHg, PaCO₂ = 38 ± 1.2 mmHg and pH = 7.32 ± 0.02) were similar in the three groups of rats and did not change significantly over time after the experimental procedure. Necropsy was carried out 149 ± 15 days after the experimental intervention. No cerebral aneurysms were found in the rats with carotid ligation or which had been sham-operated, however, three of the eight rats (p < 0.05) with carotid anastomosis presented single aneurysms in the anterior cerebral-anterior communicating arterial complex. These results indicate that haemodynamic stress correlates with cerebral aneurysm development and suggest that aneurysms may, in fact, be induced by high, unilateral carotid blood flow which provokes cerebrovascular injury.

Supported by the Grant from the Spanish Social Security Research Fund FISS 916/84.