Carotid endarterectomy shunting. Effectiveness determined by operative ocular pneumoplethysmography

The theoretical advantages and practical disadvantages of carotid endarterectomy shunting are well known. To assess shunt physiology, we performed operative ocular pneumoplethysmography on six patients before carotid clamping, during carotid clamping, during carotid shunting, and on completion of carotid repair. In each case the shunt functioned, at best, as a vessel with at least a 75% or greater cross-sectional area stenosis. However, in all cases it appreciably elevated the ipsilateral ophthalmic systolic pressure over that noted during carotid clamping. There is no question that carotid shunting provides a margin of safety during prolonged carotid clamping.