PDF Parameter or Index | Physiologic Analog | SI Units | Expressed as | Description |
---|---|---|---|---|
x0 | Effective volumetric load | cm | cm | Initial displacement, effectively equivalent to the E-wave VTI |
c | Viscoelastic loss index | N·s·m−1 | g/s | Friction-like force which opposes the ventricle returning to its resting state after systole |
k | Chamber stiffness | N·m−1 | g/s2 | Analogous to the spring stiffness constant, and correlated with invasive LV dP/dV |
kx0 | Maximum driving force | N | dynes or mN | The initial peak driving force of diastole. Proportional to the peak atrioventricular pressure gradient |
1/2kxo2 | Potential energy | J | ergs or mJ | Stored potential elastic energy to generate rapid recoil during early filling |
cEpeak | Peak resistive force | N | mN | The initial peak resistive force of diastole. Resistive (viscoelastic) force at peak flow |
M | Load independent index of diastolic filling | N/N | unitless | Unitless ratio of maximum driving force to peak resistive force (kx0/cEpeak) |
c2-4k | Damping index β |  | g2/s2 | Relative contribution between damping (c) and recoil (k). Negative values reflect underdamped filling, positive values reflect overdamped filling |
KFEI | Kinematic filling efficiency index | cm/cm | unitless | Ratio of the VTI of the acquired E-wave contour fit via PDF to the VTI of the PDF model-predicted ideal E-wave contour with no resistance to filling (c = 0) |
Slope intercept B | Maximum driving force for cEpeak = 0 | N | mN | y-intercept of the equation: kxo = M·cEpeak + B; peak driving force in the setting of no resistance, related to LVEDP |