Overview

After heart disease then cancer, stroke is the third leading cause of death in the Western world. 20% of strokes are haemorrhagic, 80% are ischaemic – mostly due to embolus but some due to small vessel disease in the brain and occasionally from prothrombotic disorders such as myeloma or sickle cell. Main sources of emboli:

• Left atrium or ventricle (‘cardiogenic’).
  
• Aortic arch.
  
• Middle cerebral artery.
  
• Carotid artery.
  
• Vertebral artery.

It is disease in the carotid artery that has relevance to vascular surgery. A stenosis in the carotid causes problems because there is potential debris that could embolise to the cerebral circulation (the reduced flow to the brain from the stenosis is of relatively little significance because there is good collateral supply).

The Anterior and Posterior Cerebral Circulation

The carotids serve the anterior part of the brain whereas the vertebral arteries serve the posterior part of the brain. It is crucial to establish if the patient’s symptoms are from the anterior circulation (or carotid territory) or posterior circulation (or vertebrobasilar territory), because surgery may be offered for the carotid but not the vertebral.