Effects of carotid endarterectomy on blood flow in the internal carotid artery

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Abstract
A retrospective study of patients operated upon for carotid stenosis was undertaken with special emphasis on the internal carotid artery (ICA) blood flow. A total of 212 endarterectomies were performed in 198 patients. The overall operative mortality was 1.4%, and the cerebral morbidity was 2.8%. A temporary inlying shunt was used routinely during endarterectomy. In two of 198 endarterectomies the shunt itself could not be excluded as a possible cause of postoperative neurological deficits. The ICA blood flow before and after endarterectomy was determined by electromagnetic flowmetry in 160 operations. Flow measurements were compared in TIA and stroke patients, in patients with high and low degrees of luminal constriction, and in patients with occluded or “open” (minimal stenosis) contralateral ICA. The results indicate that the preoperative blood flow, as well as the increase in blood flow after removal of the stenosis, is determined not only by the degree of luminal constriction, but also by the magnitude of blood flow from all precerebral feeding arteries and their intracranial collateral circulation. In treatment of carotid stenosis critical evaluation of symptoms, angiography, and haemodynamics are essential. Endarterectomy is beneficial because an embolic source is removed, and probably because perfusion is improved to areas of the brain with marginal circulation. The main factors regulating the normal cerebral perfusion are cardiac output (mean perfusion pressure), arterial pCO2 and pO2, haematocrit, and the arterial and venous blood pressures. Comparatively few investigations have been published on the effect of endarterectomy upon internal carotid artery (ICA) blood flow4, 12, 14, 27. Since 1970 we have routinely measured the ICA blood flow before and after endarterectomy18. This paper reviews the clinical and haemodynamic results of our patients operated on for carotid stenosis.