title: Proximal arterial occlusion protects the distal lower limb vessels.
abstract: OBJECTIVE
  To test the hypothesis that chronic arterial occlusion protects the distal vessels from disease progression.
  
  
  METHODS
  Peripheral angiograms from the radiology film store filed under 1997-1999 were reviewed. Those showing unilateral iliac occlusion and those showing unilateral femoro-popliteal occlusion were selected. The severity of arterial disease distal to the occlusion was compared with the patent side. Subsequently, in a subgroup of patients undergoing repeat angiography, the frequency and distribution of disease progression was recorded and related to the initial disease distribution.
  
  
  RESULTS
  In the presence of a unilateral iliac occlusion, femoro-popliteal occlusion was less likely on the side of the iliac occlusion than on the opposite side (difference in proportion 10%. 95% C.I.: 1-18%). In the presence of a unilateral occlusion proximal to the knee joint, there were more patent calf vessels on the side of the occlusion than on the opposite side (difference in proportion 9%. 95% C.I.: 4-14%). When angiography was repeated, progression of calf vessel disease was less common in the limbs with untreated proximal occlusion than in those with no proximal occlusion.
  
  
  CONCLUSIONS
  Proximal arterial occlusion protects the distal vessels from the risk of progressive arterial disease.
mesh_terms: D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D002908:Chronic Disease; D018450:Disease Progression; D005263:Femoral Artery / Q000473:pathology; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging; D007866:Leg / Q000098:blood supply*; D011150:Popliteal Artery / Q000000981:diagnostic imaging; D012189:Retrospective Studies