Hemodynamics
of
Large
Arteries
81
relation, the force-velocity-length
(f-v-Z)
relation has been suggested to
be able to completely describe the physical behavior
of
the muscle.
4.1.3
The Pressure-Volume Curve and Contractility of the Heart
The Frank-Starling mechanism, or better known as the “Starling’s
Law of the Heart”, has classically been regarded
as a
fundamental
property of the ventricle to regulate its cardiac output. The larger the
volume before the onset
of
contraction or preload, the higher is its output
under otherwise identical conditions. In this context, the preload has
been identified as the end-diastolic volume.
5
!
3
$
3
k
2
‘C
c1
Left
Ventricular Volume
APVR
Fig.
4.1.4
Pressure-volume (P-V) diagram
of
the left ventricle defining ventricular
elastance and
Vd.
The end-systolic pressure-volume line is drawn
as
tangent to the P-V
loop
at end-systole. Its
slope
represents the maximum elastance
of
the left ventricle,
or
Emax.
The pressure-volume relation has been popular because it provides
the inter-relationships between stroke volume
(SV),
end-diastolic volume
(EDV),
end-systolic volume
(ESV)
and ejection fraction on a single
diagram. The pressure-volume diagram (Fig.
4.1.4)
is constructed from
the instantaneous recordings
of
left ventricular pressure and volume. In
