Assessment of LV diastolic filling using color M-mode Doppler echocardiography: validation in a new hydraulic model

The effect of LV properties on v p and the E / v p ratio remains a matter of debate. Therefore, the objective of this study is to explore – in a new hydraulic model – the individual contributions of LV relaxation, filling pressure and compliance in changes of E , v p and E / v p for different stages of diastolic function. A new hydraulic model, consisting of an open cylindrical LA connected to an ellipsoidal LV, is designed. E and v p are measured for varying values of τ (45–60–90 ms), LV compliance (0.45–1.35 ml/mmHg) and filling pressure (3–10–30 mmHg). The results are used for predicting the evolution of E , v p and E / v p during different stages of diastolic function. An increase in compliance decreases E , whereas it augments v p . v p is less load-dependent than E . E decreases with delayed relaxation, increases for the case of pseudonormalisation, and becomes higher than the reference values during restrictive filling. The v p value is lower for the case of delayed relaxation than for the reference situation. During pseudonormalisation, the value of v p remains lower than the reference value but higher than the value for delayed relaxation. . v p further decreases during restrictive filling. In conclusion, the effect of simultaneous changes in compliance and loading counterbalance changes in v p . Therefore, under normal physiologic conditions where load and compliance are coupled, v p is apparently load-insensitive and E / v p increases as filling pressure increases. Moreover, in the different stages of diastolic dysfunction, due to the interference of the co-varying relaxation, the increase in E / v p is more pronounced.