88
Dynamics
of
the
Vascular
System
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nonlinear model
of
the systemic arterial system (see Section
4.5).
A
model incorporating this property to investigate the dynamic heart-
arterial system interaction
is
shown in Fig.
4.1.7.
The left ventricle is
represented by
a
time-varying compliance and
a
systolic resistance. The
time-varying compliance is the inverse of time-varying elastance. Both
time-varying compliance
of
the left ventricle and the pressure-dependent
compliance
of
the arterial system exhibit temporal dependence, hence
they are dynamic in nature.
pej_Fw
This model predicted changes have particular implications in terms
of
global heart-arterial system interaction.
For instance, the pressure-
dependent arterial compliance
(C(P))
increases during the early systole to
facilitate ventricular ejection, but reaches a minimum at about end-
systole (Fig.
4.1.8).
The dynamic elastance of the arterial system
represented as the inverse
of
the pressure-dependent arterial system
compliance is:
E,
(t)
=
1
/
C(P)
(4.1.20)
At
end-systole, is when both
time-varying arterial elastance and
ventricular elastance are at their respective maximum
(Emax,
also Berger
