title: The diastolic flow-pressure gradient relation in coronary stenoses in humans.
abstract: OBJECTIVE
  We assessed the feasibility and reproducibility of the instantaneous diastolic coronary flow velocity-pressure gradient relation to characterize different degrees of coronary stenoses.
  
  
  BACKGROUND
  Assessment of the hemodynamic significance of coronary stenoses can be difficult. Using sensor-tipped guidewires, various physiologic indexes can be determined in the catheterization laboratory. Each of the current methods, however, has limitations.
  
  
  METHODS
  After positioning a Doppler flow wire and a pressure wire distal of a coronary stenosis, the flow velocity signals and the proximal and distal pressure were sampled simultaneously, at baseline and after intracoronary administration of adenosine. The instantaneous diastolic flow velocity and pressure gradient of single cardiac cycles at baseline, at maximal and intermediate hyperemia were plotted. Data were fitted with a regression line using the equation: Delta P = 0 +kv+Sv(2). Measurements were performed in 11 normal coronary arteries, 20 intermediate stenoses and in 7 severe stenoses before and after percutaneous transluminal coronary angioplasty plus stenting.
  
  
  RESULTS
  We found significant differences between normal coronary arteries, intermediate and severe stenoses. Percutaneous transluminal coronary angioplasty nearly normalized the highly abnormal flow-pressure gradient relation in the severe stenoses. A high degree of reproducibility was observed. In 3% of the measurements, analysis was not possible due to the occurrence of pressure drift or bad flow velocity signals.
  
  
  CONCLUSIONS
  It is feasible to assess the diastolic flow velocity-pressure gradient relation over a wide range of stenoses. It characterizes the hemodynamics of epicardial coronary stenoses and allows discrimination between normal coronary arteries, intermediate and severe stenoses.
authors.affiliation: Department of Cardiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands. km.marques@VUmc.nl
authors.forename: Koen M J
authors.initials: KM
authors.lastname: Marques
authors.forename: Hugo J
authors.initials: HJ
authors.lastname: Spruijt
authors.forename: Christa
authors.initials: C
authors.lastname: Boer
authors.forename: Nico
authors.initials: N
authors.lastname: Westerhof
authors.forename: Cees A
authors.initials: CA
authors.lastname: Visser
authors.forename: Frans C
authors.initials: FC
authors.lastname: Visser
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000503:physiopathology* / Q000628:therapy; D003971:Diastole / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results