title: Comparison of transprosthetic mean pressure gradients between Medtronic Hall and ATS valves in the aortic position.
abstract: OBJECTIVE
  Several studies have shown the inferior performance of small prostheses in the narrow aortic root. However, modern low-profile mechanical prostheses have improved hemodynamic performance characteristics. By measuring the transprosthetic pressure gradient in vivo, we were able to characterize the hemodynamic features of two prostheses: the ATS Medical (ATS) and the Medtronic Hall (MH) valves.
  
  
  METHODS
  From October 1994 to April 2002, 113 patients received an aortic valve replacement (AVR) with either an ATS or a MH valve. The transprosthetic pressure gradients, calculated from a simplified Bernoulli equation during immediate postoperative Doppler echocardiographic examination, were compared for differently sized prostheses with respect to body surface area (BSA).
  
  
  RESULTS
  The mean pressure gradients and the mean BSAs were: 27.8 +/- 14.8 mm Hg and 1.50 +/- 0.10 m(2) in ATS 19 mm (n = 7), 20.4 +/- 8.5 mm Hg and 1.54 +/- 0.11 m(2) in ATS 21 mm (n = 22), 13.0 +/- 5.7 mm Hg, 1.70 +/- 0.13 m(2) in ATS 23 mm (n = 22), 10.9 +/- 3.5 mm Hg and 1.81 +/ -0.16 m(2) in ATS 25 mm (n = 19), 9.3 +/- 0.6 mm Hg and 1.72 +/- 0.17 m(2) in ATS 27 mm (n = 4), 13.5 +/- 6.5 mm Hg and 1.54 +/- 0.13 m(2) in MH 20 mm (n = 9), 10.9 +/- 4.7 mm Hg and 1.64 +/- 0.15 m(2) in MH 22 mm (n = 22), 9.3 +/- 3.1 mm Hg and 1.72 +/- 0.12 m(2) in MH 24 mm (n = 7).
  
  
  CONCLUSIONS
  With the exception of the ATS 19-mm valve, the variously sized prostheses have acceptable transprosthetic pressure gradient measurements. In addition, even-sized MH valves (20 and 22 mm) with a thinner sewing cuff showed better hemodynamic performances than similarly sized ATS valves.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery of Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Kangnam-Ku, Seoul, 135-710, South Korea.
authors.forename: Kiick
authors.initials: K
authors.lastname: Sung
authors.forename: Pyo Won
authors.initials: PW
authors.lastname: Park
authors.forename: Kay-Hyun
authors.initials: KH
authors.lastname: Park
authors.forename: Tae-Gook
authors.initials: TG
authors.lastname: Jun
authors.forename: Young Tak
authors.initials: YT
authors.lastname: Lee
authors.forename: Ji-Hyuk
authors.initials: JH
authors.lastname: Yang
mesh_terms: D001021:Aortic Valve; D001794:Blood Pressure; D005260:Female; D006350:Heart Valve Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012189:Retrospective Studies