|
x
0
|
Load
|
cm
|
Related to the load that is compressing the elastic myocardium at end systole, a prerequisite for a restoring force to arise. Closely related to the velocity time integral (VTI) of the E-wave.
|
|
k
|
Stiffness
|
g/s2 (N/m)
|
LV rigidity, or the extent to which the LV resists deformation in response to an applied force. Linearly related to chamber stiffness [3] (dP/dV), and thus influences the restoring force that drives early diastolic filling. Increased in hypertension [8].
|
|
c
|
Viscoelasticity
|
g/s (N∙s/m)
|
Energy loss or damping of LV recoil, caused by impaired relaxation and increased viscoelasticity of the myocardium. Increased in diabetes [6] and hypertension [8].
|
|
Vmax
|
E-wave peak velocity
|
m/s
|
Peak velocity of blood flow across the mitral valve during early LV filling.
|
|
kx
0
|
Peak driving force
|
mN
|
The peak force driving LV filling, analogous to the peak atrioventricular pressure gradient [14]. The product of k and x
0
,
|
|
cVmax
|
Peak resistive force
|
mN
|
The force resisting filling at peak transmitral flow. The product of c and Vmax.
|
|
1/2kxo2
|
Filling energy
|
mJ
|
Stored potential elastic energy from systole that generates rapid early LV filling. Increased in hypertension [8].
|
|
c2 − 4k or β
|
Damping index
|
g2/s2 (kg∙N/m)
|
Reflects the balance between the factors driving and resisting left ventricular filling. Values < −900 g2/s2 are a strong predictor of 1-year mortality in elderly with heart failure [9].
|
|
KFEI
|
Kinematic filling efficiency index
|
%
|
An index that characterizes the efficiency of LV filling. Calculated as the ratio of the velocity time integral of the actual E-wave to the velocity time integral of a PDF model-predicted ideal E-wave contour with no resistance to filling (c = 0) but the same stiffness (k) and load (x0) as for the original E-wave. Reduced in diabetes [7].
|
|
tau
|
Time constant of isovolumic pressure decay
|
ms
|
Tau is used to characterize LV filling based on time-resolved high fidelity invasive measurements of LV pressure. Increased in impaired relaxation. Can be approximated by combination of PDF parameters [4].
|
|
M
|
Load independent index of diastolic filling
|
unitless
|
A load independent index of diastolic filling, which is decreased in patients with diastolic dysfunction and increased LV end-diastolic pressure [5]. Describes the ratio of change in peak driving force to change in peak resistive force (Δkx0/ΔcVmax), calculated after acquiring E-waves under varying loading conditions.
|
|
B
|
Intercept
|
mN
|
An index of diastolic filling that is increased in patients with diastolic dysfunction and increased LV end-diastolic pressure [5]. Mathematically, the y-axis intercept of the relationship between the peak driving and resistive forces from E-waves acquired under varying loading conditions.
|
