Association of obliterative extracranial vascular disease with carotid sinus hyperaesthesia: a possible mechanism of transitory cerebral ischaemia.

In extensive studies of cerebral circulation it has been shown that obliterative extracranial vascular disease is associated with a particular regulatory pattern of cerebral circulation. In stenosis of the vertebral artery, of the internal carotid or in the subclavian steal syndrome, cerebral blood flow and O2 consumption was adequate under resting conditions and it is essentially the high cerebrovascular resistance which points to some derangement. The haemodynamic reserves of the brain being restricted, a sudden fall in heart rate may produce a significant decrease in the cerebral blood flow and thus bring about transitory cerebral ischaemic episodes. Twenty patients were studied in whom the production of transitory cerebral attacks was attributable to the coexistence of obliterative extracranial vascular disease and carotid sinus hypersensitivity. Elicitation of the carotid sinus reflex resulted in the production of transitory cerebral ischaemic spells together with a fall in cerebral blood flow in all cases. It is suggested that the transitory cerebral attacks are due in part of the cases to a coexistence of obliterative extracranial vascular disease and carotid sinus syncope. The majority of such patients become symptom-free if bradycardia or sinauricular or av block due to the carotid sinus hypersensitivity can be prevented by atropine therapy or pacemaker implantation.