ABSTRACT
Fundamental to caring for patients with carotid artery disease is a basic understanding of cerebrovascular anatomy and physiology as well as knowledge of the mechanisms and patterns of ischemic stroke in these patients. The brain is a highly metabolic organ, utilizing 20% of the body’s energy at rest with limited metabolic substrate reserve. This limited anaerobic capacity makes the brain intrinsically dependent upon a continuous supply of blood to meet its energy demands. The unique anatomy of the cerebrovascular system allows for instantaneous, dynamic regulation of flow through collateralization
from multiple inputs and connections. Blood will always flow from an area of high pressure into an area of a lower pressure, so that alterations in the vascular structure may alter which cerebral territories are at greatest risk by altering the pressure gradient. The healthy cerebrovascular system has developed mechanisms to compensate for external stressors that may limit the central nervous system (CNS) energy delivery or utilization. In disease, these mechanisms may be maximally stressed so that the introduction of another stressor may lead to vascular inefficiency and subsequent brain ischemia.
