title: Coronary vasomotor tone: determinants and effect on coronary angioplasty.
abstract: BACKGROUND
  Coronary artery reference diameters increase during coronary angioplasty (PTCA). However, in clinical practice, balloon selection is often based on a preceding diagnostic coronary angiogram. It is common to find that the initially selected balloon is undersized due to resting vasomotor tone. This may contribute to a suboptimal angioplasty result.
  
  
  METHODS
  Quantitative coronary angiography (QCA) was used to determine the magnitude of coronary artery vasodilatation over baseline angiography and its impact on balloon size choice. Pre-PTCA clinical and treatment variables were analyzed for their potential contribution to resting vasomotor tone.
  
  
  RESULTS
  QCA of reference coronary diameters was performed in a group of 103 patients undergoing PTCA. Post PTCA proximal and distal reference diameters significantly increased over baseline. The average increase of the proximal segment was 0.368 mm (13.6%) p < 0. 001 and of the distal segment 0.567 mm (24.8%) p < 0.001. The initial nominal balloon diameter was smaller than the post PTCA proximal segment by an average of 0.34 mm (12.6%) p < 0.001. Of the clinical and treatment variables examined age < 65 years and pre-PTCA beta blocker use, significantly affected baseline vasomotor tone p < 0.05.
  
  
  CONCLUSIONS
  Routine diagnostic angiography underestimates the true diameter of the coronary artery. Due to baseline vasomotor tone, coronary reference segments can be expected to increase approximately 13% in diameter during successful PTCA. Patients under 65 years of age and those using beta-blockers may have a significantly increased baseline vasomotor tone. Underestimation of coronary artery diameter based on initial angiography necessitated a second, larger balloon in 16.5% of cases.
authors.affiliation: George Hyman Research Building, Room 117, 108 Irving Street, N.W., Washington, D.C., 20010, USA. drott@starpower.net.
authors.forename: D
authors.initials: D
authors.lastname: Rott
authors.forename: W E
authors.initials: WE
authors.lastname: Lawson
authors.forename: O
authors.initials: O
authors.lastname: Lillis
authors.forename: J P
authors.initials: JP
authors.lastname: Dervan
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation; D002932:Cineangiography; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D003331:Coronary Vessels / Q000503:physiopathology*; D006801:Humans; D014666:Vasomotor System / Q000503:physiopathology*