title: Revisiting the simplified bernoulli equation.
abstract: BACKGROUND
  The assessment of the severity of aortic valve stenosis is done by either invasive catheterization or non-invasive Doppler Echocardiography in conjunction with the simplified Bernoulli equation. The catheter measurement is generally considered more accurate, but the procedure is also more likely to have dangerous complications.
  
  
  OBJECTIVE
  The focus here is on examining computational fluid dynamics as an alternative method for analyzing the echo data and determining whether it can provide results similar to the catheter measurement.
  
  
  METHODS
  An in vitro heart model with a rigid orifice is used as a first step in comparing echocardiographic data, which uses the simplified Bernoulli equation, catheterization, and echocardiographic data, which uses computational fluid dynamics (i.e., the Navier-Stokes equations).
  
  
  RESULTS
  For a 0.93cm(2) orifice, the maximum pressure gradient predicted by either the simplified Bernoulli equation or computational fluid dynamics was not significantly different from the experimental catheter measurement (p > 0.01). For a smaller 0.52cm(2) orifice, there was a small but significant difference (p < 0.01) between the simplified Bernoulli equation and the computational fluid dynamics simulation, with the computational fluid dynamics simulation giving better agreement with experimental data for some turbulence models.
  
  
  CONCLUSIONS
  For this simplified, in vitro system, the use of computational fluid dynamics provides an improvement over the simplified Bernoulli equation with the biggest improvement being seen at higher valvular stenosis levels.
authors.affiliation: Department of Chemical and Biological Engineering, Montana State University - Bozeman, Box 173920, Bozeman, MT 59717, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Heys
authors.forename: Nicole
authors.initials: N
authors.lastname: Holyoak
authors.forename: Anna M
authors.initials: AM
authors.lastname: Calleja
authors.forename: Marek
authors.initials: M
authors.lastname: Belohlavek
authors.forename: Hari P
authors.initials: HP
authors.lastname: Chaliki