title: The relation between transaortic pressure difference and flow during dobutamine stress echocardiography in patients with aortic stenosis.
abstract: OBJECTIVE
  To investigate the relation between transaortic pressure difference and flow in patients with aortic stenosis.
  
  
  METHODS
  50 asymptomatic patients with all grades of aortic stenosis were studied using dobutamine stress echocardiography. Individual plots of mean pressure drop against flow were drawn. Comparisons were made between grades of aortic stenosis as defined by the continuity equation.
  
  
  RESULTS
  A significant linear relation between pressure difference and flow was found in 34 patients (68%). There was a significant curvilinear relation in four (8%), while no significant regression line could be fitted in 12 (24%). In the 34 patients with linear fits, the slopes (mean (SD)) were 0.08 (0.07) in mild, 0.10 (0.04) in moderate, and 0.22 (0.16) in severe aortic stenosis (p = 0. 0055).
  
  
  CONCLUSIONS
  Transaortic pressure difference can be related directly to flow in many patients with all grades of aortic stenosis. However, there are individual differences in slope and intercept suggesting that resistance calculated at rest may not always be representative. Raw pressure drop/flow plots may be an alternative method of describing valve function.
authors.affiliation: Adult Echocardiography, Guy's and St Thomas' Hospitals, Cardiothoracic Centre, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK.
authors.forename: S
authors.initials: S
authors.lastname: Takeda
authors.forename: H
authors.initials: H
authors.lastname: Rimington
authors.forename: J
authors.initials: J
authors.lastname: Chambers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002302:Cardiac Output; D002316:Cardiotonic Agents; D004280:Dobutamine; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine