title: Aortic valve resistance as an adjunct to the Gorlin formula in assessing the severity of aortic stenosis in symptomatic patients.
abstract: OBJECTIVE
  This study was conducted to determine the utility of aortic valve resistance in assessing the severity of aortic stenosis.
  
  
  BACKGROUND
  Assessment of the severity of aortic stenosis has traditionally employed hemodynamic data and the Gorlin formula to calculate the area of the aortic valve. Recently, flow dependence of the Gorlin formula has been identified and the accuracy of the formula challenged. Aortic valve resistance, the quotient of gradient and cardiac output, has been advanced as potentially useful in assessing the severity of valve stenosis.
  
  
  METHODS
  We studied 48 symptomatic patients with an initial diagnosis of severe aortic stenosis based on a calculated aortic valve area of less than or equal to 0.8 cm2 by the Gorlin formula. Forty of these patients (Group I) were confirmed to have severe aortic stenosis, whereas 8 (Group II) were subsequently proved not to have severe aortic stenosis. The 18 patients in Group I with a valve area of 0.6 to 0.8 cm2 (Group IA) were directly compared with Group II patients who had a similar valve area.
  
  
  RESULTS
  Aortic valve area was nearly identical in Group IA and Group II patients (0.69 +/- 0.05 and 0.71 +/- 0.06 cm2, respectively, p = NS). However, aortic valve resistance was much less in Group II patients (212 +/- 6 vs. 316 +/- 11 dynes.s.cm-5, p less than 0.0001). In this small cohort, aortic valve resistance achieved nearly complete separation of patients in Groups IA and II.
  
  
  CONCLUSIONS
  In some patients with relatively mild aortic stenosis, the calculated valve area may indicate that the stenosis is severe. The use of aortic valve resistance in conjunction with the Gorlin formula helps separate patients with truly severe aortic stenosis from those with milder disease.
authors.affiliation: Cardiology Division, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston.
authors.forename: J D
authors.initials: JD
authors.lastname: Cannon
authors.forename: M R
authors.initials: MR
authors.lastname: Zile
authors.forename: F A
authors.initials: FA
authors.lastname: Crawford
authors.forename: B A
authors.initials: BA
authors.lastname: Carabello
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000473:pathology* / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000145:classification* / Q000453:epidemiology / Q000473:pathology; D006328:Cardiac Catheterization; D002302:Cardiac Output; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D009599:Nitroprusside; D010865:Pilot Projects; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013022:South Carolina / Q000453:epidemiology; D013318:Stroke Volume; D014655:Vascular Resistance
chemical_list: D009599:Nitroprusside