title: Valve replacement in aortic stenosis with preoperative mean gradient < 50 mmHg: hemodynamic outcome.
abstract: OBJECTIVE
  No prior studies have defined pre- versus postoperative hemodynamics of large numbers of patients with low mean transvalvular gradients. This was our objective.
  
  
  METHODS
  Retrospective analysis was undertaken of preoperative and postoperative echo/Doppler data in 294 patients who underwent aortic valve replacement (AVR) for aortic stenosis (AS). Some 136 patients had a preoperative mean gradient of < 50 mmHg. The relationship of preoperative to pre- minus postoperative (delta) mean gradient (GRAD), peak valvular velocity (V2), left ventricular outflow tract velocity (V1), V1/V2 ratio, V2-V1, and aortic valve area (AVA) were plotted and analyzed such that a 'zero-benefit threshold' from surgery could be estimated.
  
  
  RESULTS
  Strong relationships (r > 0.80) were noted for GRAD to delta GRAD, V2 to delta V2, and (V2-V1) to delta (V2-V1) with zero-benefit thresholds of 16 mmHg for GRAD, 2.6 m/s for V2 and 1.7 m/s for V2-V1. These thresholds were lower in patients who received homografts (11 mmHg, 2.2 m/s, and 1.1 m/s respectively), p < 0.02. The relationship of pre operative V1/V2 to delta V1/V2 and AVA-delta AVA were weaker (r = 0.52 and 0.33 respectively) with zero-benefit thresholds of 0.41 and 2.0 cm2. Among patients with depressed preoperative fractional shortening, improvement was confined to those without coexistent coronary artery disease.
  
  
  CONCLUSIONS
  This analysis of thresholds of mean gradient benefit suggests that most patients with low gradient AS improve hemodynamically from AVR. The hemodynamic 'break-even' point averages a mean gradient of 16 mmHg.
authors.affiliation: Mayo Clinic Jacksonville, Florida 32224, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Blackshear
authors.forename: F A
authors.initials: FA
authors.lastname: Miller
authors.forename: H
authors.initials: H
authors.lastname: Loutfi
authors.forename: S J
authors.initials: SJ
authors.lastname: Finck
authors.forename: H E
authors.initials: HE
authors.lastname: Snyder
authors.forename: R C
authors.initials: RC
authors.lastname: Agnew
authors.forename: T A
authors.initials: TA
authors.lastname: Orszulak
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000637:transplantation*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D001705:Bioprosthesis; D005260:Female; D006350:Heart Valve Prosthesis; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D014463:Ultrasonography