title: High-resolution transthoracic echocardiography of the left anterior descending coronary artery: a novel noninvasive assessment of coronary vasoreactivity.
abstract: OBJECTIVE
  The study objective was to determine the effects of salbutamol and nitroglycerin (NTG) on the luminal diameter of the left anterior descending (LAD) coronary artery, as measured noninvasively by the novel technique of high-resolution transthoracic echocardiography (HRTTE).
  
  
  BACKGROUND
  Invasive studies of the coronary arteries have demonstrated vasodilatation by salbutamol and NTG. By using a novel technique of HRTTE, combined with assessment of augmentation index (AIx, a marker of peripheral arterial stiffness) by means of applanation tonometry from the radial artery (pulse wave analysis), we studied the vasomotion of the proximal LAD in healthy volunteers.
  
  
  METHODS
  Nineteen male subjects (age 31 +/- 5 years, mean +/- standard deviation) underwent HRTTE measurement of the wall thickness, luminal diameter, and external diameter of the proximal LAD, and AIx at baseline and 5, 10, 15, and 20 minutes after administration of inhaled salbutamol (400 microg) and, after return to baseline, sublingual NTG (300 microg).
  
  
  RESULTS
  Salbutamol induced a 44% +/- 28% increase in LAD luminal diameter (2.8 +/- 0.8 mm to 3.7 +/- 0.9 mm, P < .001) and a reduction in AIx (-13.4% +/- 6.6%, P < .001). NTG induced greater changes in both parameters (60% +/- 30% increase in luminal diameter from baseline, 2.7 +/- 0.9 mm to 4.4 +/- 1.1 mm, P < .001; and reduction in AIx -24.1% +/- 8.2%, P < .001). Changes in LAD diameter and AIx were related after both salbutamol (r = -0.53, P = .02) and NTG (r = -0.57, P = .01). No significant change was detected in wall thickness.
  
  
  CONCLUSIONS
  HRTTE is able to detect the LAD coronary artery vasodilating effects of NTG and salbutamol and correlates with peripheral vascular reactivity to these vasodilators. This approach provides a useful tool for the noninvasive assessment of coronary vasoreactivity.
authors.affiliation: Cardiac Services, Flinders Medical Centre, Flinders University, Bedford Park, South Australia, Australia. rebecca.perry@fmc.sa.gov.au
authors.forename: Rebecca
authors.initials: R
authors.lastname: Perry
authors.forename: Majo X
authors.initials: MX
authors.lastname: Joseph
authors.forename: Carmine G
authors.initials: CG
authors.lastname: De Pasquale
authors.forename: Derek P
authors.initials: DP
authors.lastname: Chew
authors.forename: Derek
authors.initials: D
authors.lastname: Yiu
authors.forename: Philip E
authors.initials: PE
authors.lastname: Aylward
authors.forename: Arduino A
authors.initials: AA
authors.lastname: Mangoni
mesh_terms: D000328:Adult; D000420:Albuterol / Q000494:pharmacology*; D015331:Cohort Studies; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000187:drug effects; D017548:Echocardiography, Transesophageal / Q000379:methods*; D006801:Humans; D008297:Male; D011336:Probability; D011673:Pulsatile Flow; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D000420:Albuterol