Arteries in any part of the body may block (occlusive vascular disease). It is not limited to the lower extremities (legs). Arteriosclerosis (hardening and thickening of the artery wall) is most often associated with hypertension and diabetes. With the increase in the number of risk factors (age, diabetes, hypertension, obesity, elevated cholesterol and lipids) and an aging population, the incidence of occlusive vascular disease is rapidly increasing. The goal of surgery to correct occlusive vascular disease in the legs is the saving of life and limb. There are several procedures for treating occlusive vascular disease, but at the end of 5 years only 65 - 75% of procedures remain successful.

Anatomy

• There are three types of arteries (Figure 1):
  
  1. Large or elastic - aorta and its large branches (e.g. iliac arteries)
     
  2. Medium sized or muscular (e.g. femoral and popliteal arteries)
     
  3. Small arteries - usually less than two millimeters and within tissues of organs
     
• The walls of arteries consist of (Figure 2):
  
  1. Intima - lining cells along with minimal underlying tissue
     
  2. Internal Elastic Membrane - a dense elastic membrane that separates intima and media
     
  3. Media - smooth muscle cells
     
  4. External Elastic Membrane - an elastic membrane separating media and adventia
     
  5. Adventitia - outer connective tissue (fibrous) layer
     
• In muscular arteries, the media is composed mostly of smooth muscle cells that regulate blood flow and pressure in the tissues. Nerves that control the size of blood vessels are not under voluntary control (the autonomic nervous system). Local tissue metabolism also contributes to vessel size (e.g. carbon dioxide build up causes the vessels to dilate)
  
• Arteries serve to deliver nutrients (food) and oxygen to tissue capillaries. At rest blood flow to a normal leg averages 300 - 400 milliliters/minute (1/3 quart per minute). With moderate exercise flow increases 5 - 10 times

Figure 1 - Arteries of the leg. © J. Norah	Figure 2 - Cross-section of a normal artery and an artery with plaque. © J. Norah