title: Patient-prosthesis mismatch is negligible with modern small-size aortic valve prostheses.
abstract: BACKGROUND
  Concern has been raised about residual significant gradients when small aortic prostheses are used, particularly in patients with large body surface areas. We studied the performance of six types of small aortic prostheses using dobutamine stress echocardiography.
  
  
  METHODS
  Sixty-three patients (mean age, 67 +/- 7 years) who had undergone aortic valve replacement 17 +/- 6 months previously were studied. Two bileaflet mechanical prostheses (St. Jude Medical and CarboMedics: sizes, 19 mm and 21 mm) and two biological prostheses (Medtronic Intact and St. Jude BioImplant: size, 21 mm) were evaluated. A graded infusion of dobutamine was given and Doppler studies of valve performance were carried out.
  
  
  RESULTS
  All prostheses except one biological valve had acceptable hemodynamic performance under stress. Using regression modeling, gradient at rest was the only variable found to predict gradient under stress (p < 0.001). Moreover, the most important predictor of gradient at rest was valve design, which accounted for 72% of the variance (p < 0.001). This relationship was independent of valve size (19 mm or 21 mm) or material (ie, mechanical or biological). Body surface area accounted for 4% of the variance in gradient only.
  
  
  CONCLUSIONS
  The main predictor of transprosthetic gradient is the inherent characteristics of each particular prosthesis, with relatively insignificant contribution from variations in body surface area. Patient-prosthesis mismatch is not a problem of clinical significance when certain modern valve prostheses are used.
authors.affiliation: Bristol Heart Institute and Research and Development Support Unit, University of Bristol, England. izzat@cyberia.net.lb
authors.forename: M B
authors.initials: MB
authors.lastname: Izzat
authors.forename: I
authors.initials: I
authors.lastname: Kadir
authors.forename: B
authors.initials: B
authors.lastname: Reeves
authors.forename: P
authors.initials: P
authors.lastname: Wilde
authors.forename: A J
authors.initials: AJ
authors.lastname: Bryan
authors.forename: G D
authors.initials: GD
authors.lastname: Angelini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000601:surgery*; D001705:Bioprosthesis; D001830:Body Surface Area; D004280:Dobutamine; D015150:Echocardiography, Doppler; D019544:Equipment Failure Analysis; D005080:Exercise Test / Q000187:drug effects; D005260:Female; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D011474:Prosthesis Design; D017755:Prosthesis Fitting
chemical_list: D004280:Dobutamine