title: Subvalvular gradients in patients with valvular aortic stenosis: prevalence, magnitude, and physiological importance.
abstract: BACKGROUND
  Although subvalvular gradients in patients with aortic stenosis have been described, their behavior and response to exercise have not been well characterized.
  
  
  RESULTS
  Left ventricular and aortic pressures and linear flow velocity were measured with a catheter-tip manometer at rest and during supine exercise in 27 patients with valvular aortic stenosis. A subvalvular gradient was measured in each patient that represented, on average, 48% of the total resting transvalvular gradient. With exercise, both total (rest: 80+/-26 mm Hg; exercise: 90+/-25 mm Hg) and subvalvular gradients (rest: 37+/-13 mm Hg; exercise: 60+/-22 mm Hg) increased significantly. There was a significant inverse relationship between change in exercise cardiac output and total and subvalvular gradients. However, only the exercise subvalvular gradient predicted cardiac output response.
  
  
  CONCLUSIONS
  Subvalvular pressure gradients are universally present in patients with severe aortic stenosis and comprise approximately half of the total transvalvular gradient. The extent of exercise cardiac output increase is inversely related to the subvalvular gradient magnitude.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. wlaskey@ medicine.umaryland.edu
authors.forename: W K
authors.initials: WK
authors.lastname: Laskey
authors.forename: W G
authors.initials: WG
authors.lastname: Kussmaul
mesh_terms: D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000503:physiopathology*; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000502:physiology; D005080:Exercise Test; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008875:Middle Aged