Analysis of transmitral flow velocity contours to differentiate between alternative diastolic pressure-volume relations

Several mathematical expressions (linear, logarithmic, exponential, power law) have been proposed for the diastolic pressure-volume (P-V) relation. The P-V relation is a major component of the atrioventricular pressure gradient that determines transmitral flow. Which P-V relation applies in the in-vivo setting has not been determined by analysis of echocardiographic transmitral flow data. We sought to determine if alternative P-V relations are distinguishable via transmitral echocardiographic Doppler E-wave analysis. One-dimensional force-displacement analogues of the alternative P-V relations were used in a lumped parameter kinematic model for transmitral flow. E-waves of 17 subjects were analyzed using model-based image processing (MBIP). Root-mean-square-error determined fits of model predicted flow velocity to E-wave contours were similar regardless of the force-displacement relation used. We conclude that the simplest (linear) force-displacement relation is suitable for MBIP of transmitral Doppler flow and quantitative diastolic function assessment.