Does the simplified Bernoulli equation accurately estimate pressure gradients in regurgitant jets in an in vitro model?
The simplified Bernoulli equation may significantly underestimate pressure gradients in regurgitant jets when wall interaction is present or viscosity is increased, highlighting the need for caution in clinical application.
AIMS: 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. METHODS AND 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. CONCLUSION: 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.
Giardini et al. (2008) studied this question.