THE SUBOCCIPITAL CARREFOUR - CERVICAL AND VERTEBRAL ARTERIAL ANASTOMOSIS

PURPOSE: Our objective was to anatomically define the anastomoses betw een cervical and carotid arterial distributions (the carrefour) in the rabbit and to assess the contribution of these collaterals to cortica l blood flow (CBF) during cerebral ischemia. METHODS: Angiography was carried out in six rabbits with basilar artery occlusion using selecti ve contrast injection into the right subclavian, external carotid, and internal carotid arteries. Anastomoses were corroborated with methacr ylate vascular casts prepared in five additional rabbits, CBF was meas ured in eight rabbits by H-2 clearance after basilar artery occlusion and again after bilateral common carotid artery occlusion. Cortical DC potential was measured during ischemia in these rabbits and in anothe r 19 rabbits after additional occlusion of the cervical collateral art eries. RESULTS: A network of anastomoses between superficial and ascen ding cervical, superior intercostal, vertebral, and occipital arteries was found by angiography and corrosion casts. Additional communicatio ns in the ophthalmic, ethmoidal, and cerebellar arterial distributions are described. These pathways were found to supply a mean of 15 +/- 7 mL/100 g per minute residual CBF during three-vessel ischemia, or 24% of the preischemic CBF, Ischemic depolarization of DC potential occur red in seven of the eight rabbits with collateral CBF at a mean latenc y of 2.64 +/- 0.59 minutes and at 1.71 +/- 0.09 minutes in those witho ut. CONCLUSION: The suboccipital collateral network of the rabbit rese mbles that of humans and can contribute significantly to CBF during is chemia. The results suggest that this model may be useful for evaluati ng methods of optimizing hemodynamic control of the anastomoses in sit uations such as those encountered during endovascular therapy.