title: Distribution of intimal and medial thickening in the human right coronary artery: a study of 17 RCAs.
abstract: OBJECTIVE
  To quantify the distribution of intimal and medial thickening in human right coronary arteries (RCAs) obtained at autopsy.
  
  
  BACKGROUND
  The shear and tensile stresses created by arterial bifurcation are believed to result in eccentric fibromuscular intimal thickening that leads to atherosclerosis. Vascular curvature has been cited as a cause of atherosclerosis; however, details of the location and extent of intimal and medial thickness in the largely curved human RCA are not adequately documented.
  
  
  METHODS
  The right coronary arteries were obtained from 40 postmortem hearts and cut into 20-30 segments, each being 3-4 mm in length. Microscopic sections from the proximal, acute margin, and distal regions of the RCA were digitized around the circumference of the vessel. Seventeen arteries showed insignificant stenosis (<50%) and were selected for detailed examination.
  
  
  RESULTS
  Seventy-one percent (12/17) of proximal sections displayed eccentric intimal thickening. Normalized ensemble averaging revealed a preferential thickening on the myocardial side of the artery. At the acute margin region where curvature is most pronounced and at the distal region, 51% (8/17) of the samples showed eccentric thickening, but the ensemble average thickening in these regions showed no preferential location. In these mildly diseased arteries, the thickened intima comprised of mainly smooth muscle cells with an extracellular matrix of collagen and some elastin. A relatively uniform medial smooth muscle layer was seen at all three locations.
  
  
  CONCLUSIONS
  The proximal region of the RCA appears to be a site of intrinsic eccentric intimal thickening with maximum thickness on the myocardial side of the artery. Eccentric thickening does occur in the acute margin and distal regions; however, no distinct pattern or location was evident.
authors.affiliation: Institute of Biomaterials & Biomedical Engineering, University of Toronto, 4 Taddle Creek Road, Toronto, Ontario, Canada M55 3G9. cyal.ojha@utoronto.ca
authors.forename: M
authors.initials: M
authors.lastname: Ojha
authors.forename: R L
authors.initials: RL
authors.lastname: Leask
authors.forename: J
authors.initials: J
authors.lastname: Butany
authors.forename: K W
authors.initials: KW
authors.lastname: Johnston
mesh_terms: D000328:Adult; D000368:Aged; D001158:Arteries / Q000473:pathology; D003324:Coronary Artery Disease / Q000473:pathology*; D003331:Coronary Vessels / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017539:Tunica Intima / Q000473:pathology*; D017540:Tunica Media / Q000473:pathology*