title: Doppler echocardiography in normally functioning replacement heart valves: a literature review.
abstract: OBJECTIVE
  The English literature on replacement heart valves up to the end of 1994 was reviewed to establish normal ranges for forward function and patterns of regurgitation.
  
  
  METHODS
  A total of 48 papers were collected, but 16 were excluded leaving normative data for 14 different designs on a total of 1595 valves in the aortic and 1127 valves in the mitral position. Values for velocity, derived pressure drop, effective orifice area and pressure half-time were tabulated by annulus diameter for each class of valve.
  
  
  RESULTS
  Comparison between valve designs was difficult as a result of differences in methodology. For the aortic position, differences in velocity and derived pressure drop within one valve type were similar to those between all valve designs. The homograft and Labcor-Santiago valves appeared the least obstructive although using flow-corrected effective orifice area, there were no material differences between the valve designs. For the mitral position, there was a narrow range in mean pressure drop of 2.0 mmHg to 7.8 mmHg. Little data for the tricuspid position were available. Patterns of normal transvalvar regurgitation varied widely between the valves, but obvious transvalvar regurgitation was a feature of most mechanical valves.
  
  
  CONCLUSIONS
  Much work using standardized protocols and with appropriate hemodynamic formulae needs to be done to improve our knowledge of replacement valve function.
authors.affiliation: Department of Cardiology, Guy's Hospital, London, United Kingdom.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: N
authors.initials: N
authors.lastname: Grainger
authors.forename: J
authors.initials: J
authors.lastname: Chambers
mesh_terms: D015150:Echocardiography, Doppler; D006350:Heart Valve Prosthesis / Q000295:instrumentation; D006351:Heart Valves / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D011474:Prosthesis Design; D012189:Retrospective Studies