Abstract 13595: Echocardiographic Determination of Left Ventricular Diastatic Chamber Stiffness: Kinematic Modeling-Based Derivation With in-vivo Validation
The slope of the diastatic pressure-volume relationship (D-PVR) defines passive left ventricular (LV) stiffness K. Although K is a relative measure, an absolute measurement method (cardiac catheterization) is employed to obtain it. Echocardiography is the preferred quantitative diastolic function (DF) assessment method and Doppler E-waves can only provide relative, rather than absolute, pressure information. We hypothesized that appropriate E-wave analysis can generate the D-PVRE-wave whose slope, KE-wave, is the E-wave derived diastatic, passive chamber stiffness - a relative DF index. A validated kinematic model of filling and Bernoulli's equation were used to compute pressure and volume at diastasis, to generate D-PVRE-wave, parametrized by the kinematic model's E-wave derived indexes of stiffness (k), relaxation/viscoelasticity (c) and load (xo). For validation, simultaneous (conductance catheter) P-V and echocadiographic E-wave data from 30 subjects (444 total cardiac cycles) having normal LV ejection fraction (LVEF) and a physiologic range of LV end-diastolic pressure (LVEDP) were analyzed. For each subject, the locus of physiologically varying diastatic P-V points were fit linearly to generate D-PVRCATH with slope KCATH as catheterization derived diastatic stiffness. For each subject (15 beats average) KE-wave was compared to KCATH via linear regression yielding: KE-wave = αKCATH+ b (R2=0.90), where, α=0.98 and b = 0.03.We conclude that E-wave derived diastatic stiffness KE-wave, quantitated via kinematic modeling of filling provides an excellent estimate of simultaneous, catheterization-based, P-V defined diastatic stiffness, KCATH. Hence, in chambers at diastasis, passive LV stiffness, can be accurately determined by appropriate analysis of transmitral flow (E-wave).
- © 2011 by American Heart Association, Inc.