title: Non-invasive estimation of pressure gradients in regurgitant jets: an overdue consideration.
abstract: OBJECTIVE
  This investigation sought to discern the relative accuracy of Doppler predictions of pressure drops in regurgitant jets across a broad spectrum of conditions, using an in vitro pulsatile flow model.
  
  
  RESULTS
  We studied the accuracy of Doppler pressure gradients derived from regurgitant jet peak velocities using the simplified Bernoulli equation (SBE) using an in vitro flow model of atrio-ventricular valve regurgitation. We observed overall a good correlation (r = 0.89, P < 0.0001) with actual pressure gradient, when there is normal fluid viscosity and the jet is free of wall interaction. However, we observed various degrees of underestimation of pressure gradient by Doppler when regurgitant chamber size was reduced (P = 0.0003), when fluid viscosity was increased (P < 0.0001), or in the presence of wall interaction (P < 0.0001). Chamber compliance had no effect on the accuracy of pressure gradient prediction (P = 0.36). Significant underestimation error in pressure gradient prediction by Doppler of up to 43.2% was observed.
  
  
  CONCLUSIONS
  When jet impingement or wall interaction are present, or when viscosity is increased, caution should be used in applying the SBE to a regurgitant jet, as significant underestimation in pressure gradient prediction may occur.
authors.affiliation: Pediatric Cardiology and Adult Congenital Unit, University of Bologna, Italy. alessandro5574@iol.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giardini
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Tacy
mesh_terms: D001794:Blood Pressure; D001809:Blood Viscosity; D015150:Echocardiography, Doppler; D006351:Heart Valves / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D012107:Research Design; D016277:Ventricular Function, Left