title: Importance of endothelial function in stenotic haemodynamic responses.
abstract: OBJECTIVE
  The aim was to examine endothelium mediated flow dependence in a dynamic stenosis.
  
  
  METHODS
  The coronary circulation was modelled as a proximal compliant stenosis and a fixed distal resistance. Pressures and flow were calculated using standard haemodynamic equations. Within the stenosis, the vessel wall was composed of normal and rigid sections, and the normal section dilated proportionally with flow. From this theoretical analysis, three perfusion pressures (150, 100, and 75 mm Hg) and two distal resistances (high and low) were examined.
  
  
  RESULTS
  In a stenotic artery (93% area reduction) with high flow dependence, decreasing distal resistance increased flow substantially. At 75 mm Hg perfusion pressure, flow increased from 40.8 to 81.6 ml.min-1. With moderate flow dependence, flow increases were attenuated. Without flow dependence, flow increases were smaller, and at low perfusion pressure, flow paradoxically decreased (39.0 to 0.0 ml.min-1) when distal resistance decreased. Vasoconstriction responses with and without flow dependence were analysed. In a stenotic artery, vasoconstrictors caused a concentration dependent decrease in flow. Without flow dependence, the flow dose-response curve was shifted to the left: a lower level of arterial vasoconstriction resulted in a greater flow decrease.
  
  
  CONCLUSIONS
  The theoretical analysis shows significantly different flow responses to decreasing distal resistance and to vasoconstriction depending on endothelial function. Endothelial dysfunction may be important in the pathophysiology of angina pectoris.
authors.affiliation: Philadelphia Heart Institute, Presbyterian Medical Center, PA 19104.
authors.forename: W P
authors.initials: WP
authors.lastname: Santamore
authors.forename: D
authors.initials: D
authors.lastname: Morley
authors.forename: T N
authors.initials: TN
authors.lastname: Tulenko
authors.forename: A A
authors.initials: AA
authors.lastname: Bove
mesh_terms: D001157:Arterial Occlusive Diseases / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D006801:Humans; D008955:Models, Cardiovascular; D012039:Regional Blood Flow / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology