Space and time dependency of inertial and convective contribution to the transmitral pressure drop during ventricular filling.

We have read with much interest the recent article by Firstenberg et al. (1), which provides new insights into the comprehension of noninvasive assessment of transmitral pressure drop. In their Figure 2, the investigators display a graph demonstrating how the inclusion of inertial term in the pressure calculation allows an estimation of pressure drop across the mitral valve closely related to the invasive measurements. In contrast, the application of the steady formulation of the Bernoulli equation implies a relevant underestimation of the pressure value with a relevant phase lag of the pressure curve. However, the relative role of convective and inertial terms for pressure generation is strongly dependent on the space and temporal distribution of the two terms, thus the Doppler-derived curve of pressure represented in their Figure 2 represents only a particular case and should not be taken as a reference for normal condition. We have previously evaluated the pressure maps derived from the solution of Eulero equations applied on numerical transformed color Doppler M-mode images of the left ventricular inflow (2,3). Because the inertial and convective terms have different space-time distribution and derive from different phenomenon (acceleration and potential of velocity, respectively), care must be taken when interpreting the transmitral pressure difference between two