Can Analysis of Transmitral Flow-Velocity Contours Differentiate Between Alternative Diastolic Pressure-Volume Relations?

Several expressions have been considered for the diastolic pressure-volume (P-V) relation whose mechanical analogue is the force-length relation. How alternative P-V relations modify transmitral flow (Doppler E-wave) velocity contours has not been explored. The linear force-length term of a previously validated lumped parameter transmitral flow model was replaced by a logarithmic, exponential, or power law term for E-wave prediction. Model-based image processing (MBIP) was used for model-predicted flow vs. clinical E-wave comparison using root-mean-square-error (RSME) as an index of goodness-of-fit. RMSE of fits to [approximate]100 cm/s amplitude E-waves for linear, logarithmic, power law, and exponential relations were indistinguishable [RMSE: 4.1 + or - 1.2%, 4.9 + or - 1.4%, 5.1 + or - 2.0%, and 5.3 + or - 1.6% (mean + or - SD), respectively]. We conclude that the linear force-length relation is suitable for E-wave based quantitative diastolic function assessment with the added benefit of closed form solutions to the "inverse problem" of diastole. Conversely, it is not possible to distinguish whether a ventricle obeys a linear, power law, exponential, or logarithmic P-V relation by MBIP of E-waves.